code: def plot_pseudosections(self, column, filename=None, return_fig=False):
          
          assert column in self.data.columns
  
          g = self.data.groupby('frequency')
          fig, axes = plt.subplots(
              4, 2,
              figsize=(15 / 2.54, 20 / 2.54),
              sharex=True, sharey=True
          )
          for ax, (key, item) in zip(axes.flat, g):
              fig, ax, cb = PS.plot_pseudosection_type2(
                  item, ax=ax, column=column
              )
              ax.set_title('f: {} Hz'.format(key))
          fig.tight_layout()
          if filename is not None:
              fig.savefig(filename, dpi=300)
  
          if return_fig:
              return fig
          else:
              plt.close(fig)
docs: Create a multi-plot with one pseudosection for each frequency.
  
          Parameters
          ----------
          column : string
              which column to plot
          filename : None|string
              output filename. If set to None, do not write to file. Default:
              None
          return_fig : bool
              if True, return the generated figure object. Default: False
  
          Returns
          -------
          fig : None|matplotlib.Figure
              if return_fig is set to True, return the generated Figure object