code: def zoom(ax, xy='x', factor=1):
      
      limits = ax.get_xlim() if xy == 'x' else ax.get_ylim()
      new_limits = (0.5*(limits[0] + limits[1])
                    + 1./factor * np.array((-0.5, 0.5)) * (limits[1] - limits[0]))
      if xy == 'x':
          ax.set_xlim(new_limits)
      else:
          ax.set_ylim(new_limits)
docs: Zoom into axis.
  
      Parameters
      ----------