diff --git a/abipy/abilab.py b/abipy/abilab.py
index 1c4855c1..a5751a7b 100644
--- a/abipy/abilab.py
+++ b/abipy/abilab.py
@@ -356,7 +356,7 @@ def software_stack(as_dataframe=False):
         try:
             mod = import_module(pkg_name)
             return mod.__version__
-        except:
+        except Exception:
             return None
 
     try:
diff --git a/abipy/abio/abivars.py b/abipy/abio/abivars.py
index b718466e..b870715a 100644
--- a/abipy/abio/abivars.py
+++ b/abipy/abio/abivars.py
@@ -749,7 +749,7 @@ def structure_from_abistruct_fmt(string):
         v = xred[iatom]
         lines.append("%.16f %.16f %.16f" % (v[0], v[1], v[2]))
 
-    s =  "\n".join(head) + "\n" + "\n".join(lines) #; print(s)
+    s = "\n".join(head) + "\n" + "\n".join(lines) #; print(s)
 
     return AbinitInputFile.from_string(s).structure
 
diff --git a/abipy/abio/factories.py b/abipy/abio/factories.py
index ad66b0d7..c8e45586 100644
--- a/abipy/abio/factories.py
+++ b/abipy/abio/factories.py
@@ -1503,7 +1503,7 @@ def conduc_kerange_from_inputs(scf_input, nscf_input, tmesh, ddb_ngqpt, eph_ngqp
             sigma_kerange[0] += epad
         if e_range > 0:
             sigma_kerange[1] += epad
-    
+
     # Modify the second nscf input to get a task that calculate the kpt in the sigma interval (Kerange.nc file)
     multi[2].set_vars(optdriver=8, wfk_task='"wfk_kpts_erange"', kptopt=1,
                       sigma_ngkpt=sigma_ngkpt, einterp=einterp, sigma_erange=sigma_kerange)
diff --git a/abipy/core/kpoints.py b/abipy/core/kpoints.py
index 9c9a9b88..9bcf03c2 100644
--- a/abipy/core/kpoints.py
+++ b/abipy/core/kpoints.py
@@ -1138,7 +1138,7 @@ class KpointList(collections.abc.Sequence):
 
     def plotly(self, fig=None, **kwargs):
         """Plot k-points with plotly."""
-        from abipy.tools.plotting import plotly_wigner_seitz, plotly_brillouin_zone
+        from abipy.tools.plotting import plotly_brillouin_zone
         fold = False
         if self.is_path:
             labels = {k.name: k.frac_coords for k in self if k.name}
diff --git a/abipy/core/mixins.py b/abipy/core/mixins.py
index e319b5cb..273b58bc 100644
--- a/abipy/core/mixins.py
+++ b/abipy/core/mixins.py
@@ -729,6 +729,7 @@ abilab.enable_notebook(with_seaborn=True)
             nbformat.write(nb, fh)
             return nbpath
 
+
 class NotebookWriter(HasNotebookTools, metaclass=abc.ABCMeta):
     """
     Mixin class for objects that are able to generate jupyter_ notebooks.
@@ -850,7 +851,7 @@ class NotebookWriter(HasNotebookTools, metaclass=abc.ABCMeta):
         This function *generates* a predefined list of plotly figures with minimal input from the user.
         Relies on yield_plotly_figs implemented by the subclass to generate the figures.
         """
-        print("in plotly expose")
+        #print("in plotly expose")
 
         pn, template = self._get_panel_and_template()
         pn.config.sizing_mode = 'stretch_width'
diff --git a/abipy/core/structure.py b/abipy/core/structure.py
index 92bd4672..0985b598 100644
--- a/abipy/core/structure.py
+++ b/abipy/core/structure.py
@@ -1315,7 +1315,6 @@ class Structure(pmg_Structure, NotebookWriter):
         Args:
             with_cart_coords: True if Cartesian coordinates should be added as well.
         """
-        from collections import defaultdict
         if with_cart_coords:
             group = {symb: {"site_idx": [], "frac_coords": [], "cart_coords": []} for symb in self.symbol_set}
         else:
@@ -1339,8 +1338,8 @@ class Structure(pmg_Structure, NotebookWriter):
     @add_fig_kwargs
     def plot(self, **kwargs):
         """
-        Plot structure in 3D with matplotlib. Return matplotlib Figure
-        See plot_structure for kwargs
+        Plot structure in 3D with matplotlib. Return matplotlib Figure.
+        See plot_structure for kwargs.
         """
         from abipy.tools.plotting import plot_structure
         return plot_structure(self, **kwargs)
@@ -1348,7 +1347,7 @@ class Structure(pmg_Structure, NotebookWriter):
     @add_plotly_fig_kwargs
     def plotly(self, **kwargs):
         """
-        Plot structure in 3D with plotly. Return plotly Figure
+        Plot structure in 3D with plotly. Return plotly Figure.
         See plot_structure for kwargs
         """
         from abipy.tools.plotting import plotly_structure
diff --git a/abipy/dfpt/phonons.py b/abipy/dfpt/phonons.py
index 51ad7d58..af56d567 100644
--- a/abipy/dfpt/phonons.py
+++ b/abipy/dfpt/phonons.py
@@ -1124,8 +1124,8 @@ See also <https://forum.abinit.org/viewtopic.php?f=10&t=545>
             # Scatter plot with Bose-Einstein occupation factors for T = temp
             factor = abu.phfactor_ev2units(units)
             if temp < 1: temp = 1
-            fig.layout.annotations=[dict(text="T = %.1f K" % temp, font_size=fontsize, x=0.5, xref='paper',
-                                         xanchor='center', y=1, yref='paper', yanchor='bottom' ,showarrow=False)]
+            fig.layout.annotations = [dict(text="T = %.1f K" % temp, font_size=fontsize, x=0.5, xref='paper',
+                                           xanchor='center', y=1, yref='paper', yanchor='bottom', showarrow=False)]
             xs = np.arange(self.num_qpoints)
             for nu in self.branches:
                 ws = self.phfreqs[:, nu]
diff --git a/abipy/dfpt/vsound.py b/abipy/dfpt/vsound.py
index 82c73636..d7b2b927 100644
--- a/abipy/dfpt/vsound.py
+++ b/abipy/dfpt/vsound.py
@@ -10,7 +10,7 @@ from abipy.dfpt.ddb import DdbFile
 from abipy.dfpt.phonons import PhononBands, get_dyn_mat_eigenvec, match_eigenvectors
 from abipy.abio.inputs import AnaddbInput
 from abipy.tools.plotting import add_fig_kwargs, get_ax_fig_plt, set_visible, get_fig_plotly, get_figs_plotly, \
-    add_plotly_fig_kwargs, plotlyfigs_to_browser, push_to_chart_studio, PlotlyRowColDesc
+    add_plotly_fig_kwargs, plotlyfigs_to_browser, PlotlyRowColDesc
 from pymatgen.core.units import bohr_to_angstrom, eV_to_Ha
 
 
@@ -353,10 +353,10 @@ class SoundVelocity(Has_Structure, NotebookWriter):
 
         if fig is None:
             fig, _ = get_fig_plotly()
-            fig.layout=dict(annotations=[dict(text=title, font_size=fontsize, x=0.5, xref='paper', xanchor='center',
-                                         y=1, yref='paper', yanchor='bottom' ,showarrow=False)],
-                            yaxis_title_text=abu.wlabel_from_units(units, unicode=True),
-                            xaxis_title_text= "Wave Vector")
+            fig.layout = dict(annotations=[dict(text=title, font_size=fontsize, x=0.5, xref='paper', xanchor='center',
+                              y=1, yref='paper', yanchor='bottom' ,showarrow=False)],
+                              yaxis_title_text=abu.wlabel_from_units(units, unicode=True),
+                              xaxis_title_text="Wave Vector")
         else:
             fig.layout.annotations[idir].text = title
             fig.layout.annotations[idir].font.size = fontsize
@@ -429,7 +429,7 @@ class SoundVelocity(Has_Structure, NotebookWriter):
                                  horizontal_spacing=0.05)
 
         for i in range(self.n_directions):
-            rcd = PlotlyRowColDesc(i//2, i%2, nrows, ncols)
+            rcd = PlotlyRowColDesc(i // 2, i % 2, nrows, ncols)
             self.plotly_fit_freqs_dir(i, fig, rcd, units=units, fontsize=fontsize, show=False)
 
         return fig
diff --git a/abipy/dynamics/hist.py b/abipy/dynamics/hist.py
index 73e9ba47..5d938e8d 100644
--- a/abipy/dynamics/hist.py
+++ b/abipy/dynamics/hist.py
@@ -449,7 +449,6 @@ class HistFile(AbinitNcFile, NotebookWriter):
     #    yield self.plotly(show=False)
     #    yield self.plotly_energies(show=False)
 
-
     def mvplot_trajectories(self, colormap="hot", sampling=1, figure=None, show=True,
                             with_forces=True, **kwargs):  # pragma: no cover
         """
diff --git a/abipy/electrons/denpot.py b/abipy/electrons/denpot.py
index ea47acce..488be854 100644
--- a/abipy/electrons/denpot.py
+++ b/abipy/electrons/denpot.py
@@ -1,7 +1,7 @@
 # coding: utf-8
 """Density/potential files in netcdf/fortran format."""
 import os
-import tempfile
+#import tempfile
 #import numpy as np
 
 from monty.string import marquee
diff --git a/abipy/electrons/ebands.py b/abipy/electrons/ebands.py
index 4274c213..f6a0aad5 100644
--- a/abipy/electrons/ebands.py
+++ b/abipy/electrons/ebands.py
@@ -1410,7 +1410,7 @@ class ElectronBands(Has_Structure):
 
         if unicode:
             import re
-            numl=re.findall(r'\d', formula)
+            numl = re.findall(r'\d', formula)
             for s in numl:
                 formula = formula.replace(s,SUBSCRIPT_UNICODE[s])
 
@@ -1459,7 +1459,6 @@ class ElectronBands(Has_Structure):
                 k0_list.append(k)
                 effmass_bands_f90.append(v)
 
-
         # Set small values to zero.
         k0_list = np.reshape(k0_list, (-1, 3))
         k0_list = np.where(np.abs(k0_list) > 1e-12, k0_list, 0.0)
@@ -2105,7 +2104,7 @@ class ElectronBands(Has_Structure):
         ply_row, ply_col = rcd.ply_row, rcd.ply_col
 
         # Decorate the axis (e.g add ticks and labels).
-        self.decorate_plotly(fig, klabels=klabels, iax = rcd.iax)
+        self.decorate_plotly(fig, klabels=klabels, iax=rcd.iax)
         plotly_set_lims(fig, ylims, "y")
 
         # Plot the band energies.
@@ -2386,12 +2385,12 @@ class ElectronBands(Has_Structure):
                 fig.add_scatter(x=xx, y=yy, mode="lines", name=label, showlegend=showlegend, line=line_opts, **kwargs,
                                 row=ply_row, col=ply_col)
                 label = ''
-                showlegend=False
+                showlegend = False
 
                 if with_linewidths:
                     w = self.linewidths[spin, :, band] * lw_fact / 2
-                    lw_color = lines[-1].get_color()
                     raise NotImplementedError
+                    #lw_color = lines[-1].get_color()
                     # solution 1: Use scater points to fill
                     # solution 2: add two traces and fill the area between
                     # color problem
@@ -3978,7 +3977,7 @@ class ElectronDos(object):
             fig.add_scatter(x=x, y=y, mode='lines', name=trace_name, showlegend=showlegend, line=opts, **kwargs)
 
         xlabel, ylabel = 'Energy (eV)', 'DOS (states/eV)'
-        if exchange_xy: xlabel, ylabel =  ylabel, xlabel
+        if exchange_xy: xlabel, ylabel = ylabel, xlabel
         fig.layout.xaxis.title = xlabel
         fig.layout.yaxis.title = ylabel
         plotly_set_lims(fig, xlims, "x")
diff --git a/abipy/eph/rta.py b/abipy/eph/rta.py
index beda56a8..bb61a5ca 100644
--- a/abipy/eph/rta.py
+++ b/abipy/eph/rta.py
@@ -625,7 +625,8 @@ class RtaRobot(Robot, RobotWithEbands):
     #def get_mobility_mu_dataframe(self, eh=0, component='xx', itemp=0, spin=0, **kwargs):
 
     @add_fig_kwargs
-    def plot_mobility_kconv(self, eh=0, bte=['serta','mrta','ibte'], component='xx', itemp=0, spin=0, fontsize=14, ax=None, **kwargs):
+    def plot_mobility_kconv(self, eh=0, bte=('serta', 'mrta', 'ibte'), component='xx', itemp=0, spin=0,
+                            fontsize=14, ax=None, **kwargs):
         """
         Plot the convergence of the mobility as a function of the number of k-points,
         for different transport formalisms included in the computation.
@@ -662,9 +663,9 @@ class RtaRobot(Robot, RobotWithEbands):
             if 'serta' in bte:
                 mob_serta = ncfile.reader.read_variable("mobility_mu")[0, spin, itemp, eh, j, i]
             if 'mrta' in bte:
-                mob_mrta  = ncfile.reader.read_variable("mobility_mu")[1, spin, itemp, eh, j, i]
+                mob_mrta = ncfile.reader.read_variable("mobility_mu")[1, spin, itemp, eh, j, i]
             if 'ibte' in bte:
-                mob_ibte  = ncfile.reader.read_variable("ibte_mob")[spin, itemp, eh, j, i]
+                mob_ibte = ncfile.reader.read_variable("ibte_mob")[spin, itemp, eh, j, i]
 
             res.append([kptrlattx, mob_serta, mob_mrta, mob_ibte])
             temps.append(ncfile.tmesh[itemp])
@@ -789,7 +790,7 @@ class RtaRobot(Robot, RobotWithEbands):
         #if self.all_have_ibte:
         yield self.plot_ibte_mrta_serta_conv(show=False)
         yield self.plot_ibte_vs_rta_rho(show=False)
-       
+
         # Determine the independent component. For the time being,
         # only consider the cubic case separately
         abifile = self.abifiles[0]
diff --git a/abipy/examples/flows/run_becs_and_epsilon_vs_kpts.py b/abipy/examples/flows/run_becs_and_epsilon_vs_kpts.py
index 92c6f2f9..dc06e2df 100755
--- a/abipy/examples/flows/run_becs_and_epsilon_vs_kpts.py
+++ b/abipy/examples/flows/run_becs_and_epsilon_vs_kpts.py
@@ -15,6 +15,7 @@ import abipy.data as abidata
 
 from abipy import flowtk
 
+
 def make_scf_input(ngkpt, paral_kgb=0):
     """
     This function constructs the input file for the GS calculation for a given IBZ sampling.
diff --git a/abipy/examples/flows/run_eph_mob.py b/abipy/examples/flows/run_eph_mob.py
index 41439c1b..982d43f1 100755
--- a/abipy/examples/flows/run_eph_mob.py
+++ b/abipy/examples/flows/run_eph_mob.py
@@ -13,8 +13,6 @@ import abipy.abilab as abilab
 import abipy.flowtk as flowtk
 import abipy.core.abinit_units as abu
 
-from abipy.abilab import abiopen
-
 
 def build_flow(options):
     # Working directory (default is the name of the script with '.py' removed and "run_" replaced by "flow_")
diff --git a/abipy/examples/flows/run_nonlinear.py b/abipy/examples/flows/run_nonlinear.py
index 0a9150e7..f520f9b4 100755
--- a/abipy/examples/flows/run_nonlinear.py
+++ b/abipy/examples/flows/run_nonlinear.py
@@ -14,6 +14,7 @@ from abipy import abilab
 
 # NB: This flow requires abinit >= "8.5.2"
 
+
 def make_scf_input(ecut=10, ngkpt=(8, 8, 8)):
     """
     This function constructs an `AbinitInput` for performing a
diff --git a/abipy/examples/flows/run_phonopy_si.py b/abipy/examples/flows/run_phonopy_si.py
index 0d0b3dae..837021ce 100755
--- a/abipy/examples/flows/run_phonopy_si.py
+++ b/abipy/examples/flows/run_phonopy_si.py
@@ -1,10 +1,11 @@
 #!/usr/bin/env python
 r"""
-Phonopy + Abinit Flow
-=====================
+Phonopy with AbiPy Flow
+=======================
 
 This example shows how to compute phonon frequencies with phonopy
 (supercells and finite-difference method).
+
 This approach could be useful to obtain vibrational properties with XC functionals
 for which DFPT is not yet implemented.
 
diff --git a/abipy/examples/plot/plot_a2f.py b/abipy/examples/plot/plot_a2f.py
index 88d14aee..3be39044 100755
--- a/abipy/examples/plot/plot_a2f.py
+++ b/abipy/examples/plot/plot_a2f.py
@@ -11,7 +11,7 @@ import abipy.data as abidata
 
 phdos_path = abidata.ref_file("al_161616q_PHDOS.nc")
 
-ncfile =  abilab.abiopen(abidata.ref_file("al_888k_161616q_A2F.nc"))
+ncfile = abilab.abiopen(abidata.ref_file("al_888k_161616q_A2F.nc"))
 print(ncfile)
 
 #ncfile.phbands.plot()
diff --git a/abipy/flowtk/tasks.py b/abipy/flowtk/tasks.py
index 26000e53..753bd9eb 100644
--- a/abipy/flowtk/tasks.py
+++ b/abipy/flowtk/tasks.py
@@ -582,7 +582,7 @@ qadapters:
             qname: localhost
       job:
         mpi_runner: mpirun
-        pre_run:  
+        pre_run:
             # List of shell commands executed before running abinit
             # Change this part according to your Abinit installation and the location of the shared libs
             - export OMP_NUM_THREADS=1
@@ -623,15 +623,15 @@ Cannot locate `{cls.YAML_FILE}` neither in current directory nor in `{path}`
 
 !!! PLEASE READ THIS !!!
 
-    To run AbiPy flows you need a manager.yaml describing your computer/cluster 
+    To run AbiPy flows you need a manager.yaml describing your computer/cluster
     as well as the job submission engine being used (shell, Slurm, PBS, etc).
-    
+
     Examples are provided in the `abipy/data/managers` directory.
     Use `abidoc.py manager` to access the documentation from the terminal.
     See also https://abinit.github.io/abipy/workflows/manager_examples.html for examples.
-    
+
 A minimalistic example of manager.yml for a laptop with the shell engine is reported below:
-    
+
 {cls.get_simple_manager()}
 
 """, color="red"))
@@ -3945,7 +3945,8 @@ class KerangeTask(AbinitTask):
     """
     Class for kerange calculations.
     """
-    color_rgb = np.array((255, 128, 0)) / 255
+    color_rgb = np.array((255, 128, 128)) / 255
+
 
 class ManyBodyTask(AbinitTask):
     """
diff --git a/abipy/flowtk/works.py b/abipy/flowtk/works.py
index 9c25aec6..14a9028d 100644
--- a/abipy/flowtk/works.py
+++ b/abipy/flowtk/works.py
@@ -468,9 +468,9 @@ class NodeContainer(metaclass=abc.ABCMeta):
             kwargs.update({"manager": seq_manager})
 
         if eph_inp.get("eph_task",0) == -4:
-            max_cores   = TaskManager.from_user_config().qadapter.max_cores
-            natom3      = 3 * len(eph_inp.structure)
-            nprocs      = max(max_cores - max_cores % natom3, 1)
+            max_cores = TaskManager.from_user_config().qadapter.max_cores
+            natom3 = 3 * len(eph_inp.structure)
+            nprocs = max(max_cores - max_cores % natom3, 1)
             new_manager = TaskManager.from_user_config().new_with_fixed_mpi_omp(nprocs, 1)
             kwargs.update({"manager": new_manager})
 
diff --git a/abipy/integration_tests/itest_phonons.py b/abipy/integration_tests/itest_phonons.py
index 2c9f124b..c00ca871 100644
--- a/abipy/integration_tests/itest_phonons.py
+++ b/abipy/integration_tests/itest_phonons.py
@@ -160,7 +160,7 @@ def itest_phonon_restart(fwp):
         tolvrs=1.0e-5,
     )
 
-    multi = abilab.MultiDataset(structure=structure, 
+    multi = abilab.MultiDataset(structure=structure,
                                 pseudos=abidata.pseudos("13al.981214.fhi", "33as.pspnc"),
                                 ndtset=1 + len(qpoints))
 
diff --git a/abipy/panels/core.py b/abipy/panels/core.py
index 4ff1f6d3..44a59133 100644
--- a/abipy/panels/core.py
+++ b/abipy/panels/core.py
@@ -77,7 +77,7 @@ def get_template_cls_from_name(name):
     if hasattr(pn.template, name):
         return getattr(pn.template, name)
 
-    try_name =  name + "Template"
+    try_name = name + "Template"
     if hasattr(pn.template, try_name):
         return getattr(pn.template, try_name)
 
@@ -87,7 +87,6 @@ Possible templates are: {list(pn.template.__dict__.keys())}
 """)
 
 
-
 def depends_on_btn_click(btn_name):
 
     def decorator(func):
@@ -190,9 +189,11 @@ If everything is properly configured, a new window is automatically created in y
 """)
 
         btn = pnw.Button(name="Upload to chart studio server")
+
         def push_to_cs(event):
             with ButtonContext(btn):
                 push_to_chart_studio(fig)
+
         btn.on_click(push_to_cs)
 
         if with_help:
@@ -397,7 +398,6 @@ class AbipyParameterized(param.Parameterized):
 Please **refresh** the page using the refresh button of the browser if plotly figures are not shown.
 """)
 
-
     #def __repr__(self):
     #    # https://github.com/holoviz/param/issues/396
     #    return f"AbiPyParametrized(name='{self.name}')"
@@ -516,7 +516,6 @@ class HasStructureParams(AbipyParameterized):
                                             objects=[None, "jsmol", "vesta", "xcrysden", "vtk", "crystalk", "ngl",
                                                      "matplotlib", "plotly", "ase_atoms", "mayavi"])
 
-
     #def __init__(self, **params):
     #    self.struct_view_btn = pnw.Button(name="View structure", button_type='primary')
     #    super(self).__init__(**params)
@@ -639,7 +638,7 @@ def get_structure_info(structure):
     df_len = pd.DataFrame(rows, index=["Å", "Bohr"]).transpose().rename_axis("Lattice lenghts")
 
     # Build dataframe with lattice angles.
-    rows = []; keys =  ("alpha", "beta", "gamma")
+    rows = []; keys = ("alpha", "beta", "gamma")
     rows.append({k: d[k] for k in keys})
     rows.append({k: np.radians(d[k]) for k in keys})
     df_ang = pd.DataFrame(rows, index=["Degrees", "Radians"]).transpose().rename_axis("Lattice angles")
@@ -713,7 +712,7 @@ class PanelWithElectronBands(AbipyParameterized):
     # e-DOS plot.
     edos_method = param.ObjectSelector(default="gaussian", objects=["gaussian", "tetra"], doc="e-DOS method")
     edos_step_ev = param.Number(0.1, bounds=(1e-6, None), step=0.1, doc='e-DOS step in eV')
-    edos_width_ev = param.Number(0.2, step=0.05, bounds=(1e-6, None), doc='e-DOS Gaussian broadening in eV' )
+    edos_width_ev = param.Number(0.2, step=0.05, bounds=(1e-6, None), doc='e-DOS Gaussian broadening in eV')
 
     # SKW interpolation of the KS band energies.
     skw_lpratio = param.Integer(5, bounds=(1, None))
diff --git a/abipy/panels/ddb.py b/abipy/panels/ddb.py
index 4a9710dc..dc22b8c8 100644
--- a/abipy/panels/ddb.py
+++ b/abipy/panels/ddb.py
@@ -600,6 +600,7 @@ class DdbRobotPanel(BaseRobotPanel, HasAnaddbParams):
         """Return tabs with widgets to interact with the DDB file."""
         robot = self.robot
 
+        d = {}
         d["Summary"] = pn.Row(
             bkw.PreText(text=robot.to_string(verbose=self.verbose), sizing_mode="scale_both")
         )
diff --git a/abipy/panels/hist.py b/abipy/panels/hist.py
index 381d19f0..d43d2770 100644
--- a/abipy/panels/hist.py
+++ b/abipy/panels/hist.py
@@ -4,7 +4,7 @@ import panel as pn
 import panel.widgets as pnw
 import bokeh.models.widgets as bkw
 
-from abipy.panels.core import AbipyParameterized, ButtonContext, mpl, ply, depends_on_btn_click
+from abipy.panels.core import AbipyParameterized, mpl, ply, depends_on_btn_click
 
 
 _what_list = ["pressure", "forces", "energy", "abc", "angles", "volume"]
diff --git a/abipy/panels/outputs.py b/abipy/panels/outputs.py
index d1a511b1..de516dcb 100644
--- a/abipy/panels/outputs.py
+++ b/abipy/panels/outputs.py
@@ -4,7 +4,7 @@
 import panel as pn
 #import panel.widgets as pnw
 import bokeh.models.widgets as bkw
-from abipy.panels.core import AbipyParameterized, mpl, ply, dfc #, ButtonContext
+from abipy.panels.core import AbipyParameterized, mpl, ply, dfc
 
 
 class AbinitOutputFilePanel(AbipyParameterized):
diff --git a/abipy/panels/phonons.py b/abipy/panels/phonons.py
index 476dc13c..a9eac37f 100644
--- a/abipy/panels/phonons.py
+++ b/abipy/panels/phonons.py
@@ -3,7 +3,7 @@ import param
 import panel as pn
 import panel.widgets as pnw
 
-from abipy.panels.core import AbipyParameterized, ButtonContext, mpl, ply, dfc, depends_on_btn_click
+from abipy.panels.core import AbipyParameterized, mpl, ply, dfc, depends_on_btn_click
 
 
 class PhononBandsPlotterPanel(AbipyParameterized):
diff --git a/abipy/panels/structure.py b/abipy/panels/structure.py
index b366210a..18d8e1a8 100644
--- a/abipy/panels/structure.py
+++ b/abipy/panels/structure.py
@@ -5,7 +5,7 @@ import panel as pn
 import panel.widgets as pnw
 import bokeh.models.widgets as bkw
 
-from abipy.panels.core import HasStructureParams, ButtonContext, dfc, mpl, ply, depends_on_btn_click
+from abipy.panels.core import HasStructureParams, dfc, mpl, ply, depends_on_btn_click
 
 
 class StructurePanel(HasStructureParams):
diff --git a/abipy/scripts/abicomp.py b/abipy/scripts/abicomp.py
index e7265051..9190a9c5 100755
--- a/abipy/scripts/abicomp.py
+++ b/abipy/scripts/abicomp.py
@@ -676,9 +676,9 @@ def _invoke_robot(options):
             if options.plotly:
                # plotly version.
                if hasattr(robot, "plotly_expose"):
-                   robot.plotly_expose(chart_studio=options.chart_studio, verbose=options.verbose)
+                    robot.plotly_expose(chart_studio=options.chart_studio, verbose=options.verbose)
                else:
-                   cprint("<%s> does not implement plotly_expose method" % type(robot), color="red")
+                    cprint("<%s> does not implement plotly_expose method" % type(robot), color="red")
 
             elif hasattr(robot, "expose"):
                 # matplotlib version.
diff --git a/abipy/tools/devtools.py b/abipy/tools/devtools.py
index 9c187931..5b330012 100644
--- a/abipy/tools/devtools.py
+++ b/abipy/tools/devtools.py
@@ -123,6 +123,8 @@ def display_top(snapshot, key_type='lineno', limit=3):
         snapshot = tracemalloc.take_snapshot()
         display_top(snapshot)
     """
+    import tracemalloc
+    import linecache
     snapshot = snapshot.filter_traces((
         tracemalloc.Filter(False, "<frozen importlib._bootstrap>"),
         tracemalloc.Filter(False, "<unknown>"),
diff --git a/abipy/tools/plotting.py b/abipy/tools/plotting.py
index 5faedd84..5e5c283d 100644
--- a/abipy/tools/plotting.py
+++ b/abipy/tools/plotting.py
@@ -566,7 +566,7 @@ class PanelExpose(object): # pragma: no cover
         self.verbose = verbose
 
         if self.verbose:
-           print("\nLoading all figures before showing them. It may take some time...")
+            print("\nLoading all figures before showing them. It may take some time...")
 
         self.start_time = time.time()
 
@@ -979,7 +979,7 @@ class PlotlyRowColDesc(object):
         # Assume list with 4 integers
         try:
             return cls(*obj)
-        except exc:
+        except Exception as exc:
             raise TypeError(f"Dont know how to convert `{type(obj)}` into `{cls}`")
 
     def __init__(self, py_row, py_col, nrows, ncols):
@@ -1328,6 +1328,7 @@ def push_to_chart_studio(figs):
 ####################################################
 import plotly.graph_objects as go
 
+
 def go_points(points, size=4, color="black", labels=None, **kwargs):
 
     #textposition = 'top right',
@@ -1486,7 +1487,6 @@ def plot_fcc_prim():
     fcc_conv = np.array([[1, 0, 0], [0, 1, 0], [0, 0, 1]])
     fcc_conv_box = get_box(fcc_conv, name="conv lattice")
 
-
     fig = go.Figure(data=[*fcc_prim_box, *fcc_prim_vectors, *fcc_conv_box, atoms])
 
     return fig
diff --git a/requirements-optional.txt b/requirements-optional.txt
index 872f7d5f..32c1bab2 100644
--- a/requirements-optional.txt
+++ b/requirements-optional.txt
@@ -1,4 +1,3 @@
-ipython
 jupyter
 nbformat
 pygments
@@ -11,7 +10,6 @@ ase
 param
 panel
 bokeh
-chart-studio
 XlsxWriter  # For DataFrame.to_excel()
 # Unit tests
 python-coveralls
diff --git a/tasks.py b/tasks.py
index 72b7c2ee..4daa948f 100644
--- a/tasks.py
+++ b/tasks.py
@@ -59,10 +59,15 @@ pytest -n 2 --cov-config=.coveragerc --cov=abipy -v --doctest-modules abipy \
 def style(ctx):
     with cd(ABIPY_ROOTDIR):
         ctx.run("pycodestyle 2>&1 | tee style.log", pty=True)
-        ctx.run("flake8 --count --show-source --statistics | tee -a style.log", pty=True)
         #ctx.run("pydocstyle abipy | tee -a style.log", pty=True)
 
 
+@task
+def flake(ctx):
+    with cd(ABIPY_ROOTDIR):
+        ctx.run("flake8 --count --show-source --statistics | tee -a style.log", pty=True)
+
+
 @task
 def plots(ctx):
     with cd(os.path.join(ABIPY_ROOTDIR, "abipy", "examples")):