code: def _init_figure(ax, figsize):
      
      if not ax:
          fig = plt.figure(figsize=figsize)
          return fig
docs: Initializes the ``matplotlib`` ``figure``, one of the first things that every plot must do. No figure is
      initialized (and, consequentially, the ``figsize`` argument is ignored) if a pre-existing ``ax`` is passed to
      the method. This is necessary for ``plt.savefig()`` to work.
  
      Parameters
      ----------
      ax : None or cartopy GeoAxesSubplot instance
          The current axis, if there is one.
      figsize : (x_dim, y_dim) tuple
          The dimension of the resultant plot.
  
      Returns
      -------
      None or matplotlib.Figure instance
          Returns either nothing or the underlying ``Figure`` instance, depending on whether or not one is initialized.