code: def mark_inset(parent_axes, inset_axes, loc1, loc2, **kwargs):
      """
      Draw a box to mark the location of an area represented by an inset axes.
  
      This function draws a box in *parent_axes* at the bounding box of
      *inset_axes*, and shows a connection with the inset axes by drawing lines
      at the corners, giving a "zoomed in" effect.
  
      Parameters
      ----------
      parent_axes : `matplotlib.axes.Axes`
          Axes which contains the area of the inset axes.
  
      inset_axes : `matplotlib.axes.Axes`
          The inset axes.
  
      loc1, loc2 : {1, 2, 3, 4}
          Corners to use for connecting the inset axes and the area in the
          parent axes.
  
      **kwargs
          Patch properties for the lines and box drawn:
          %(Patch)s
  
      Returns
      -------
      pp : `matplotlib.patches.Patch`
          The patch drawn to represent the area of the inset axes.
  
      p1, p2 : `matplotlib.patches.Patch`
          The patches connecting two corners of the inset axes and its area.
      """
      rect = TransformedBbox(inset_axes.viewLim, parent_axes.transData)
  
      fill = kwargs.pop("fill", False)
      pp = BboxPatch(rect, fill=fill, **kwargs)
      parent_axes.add_patch(pp)
  
      p1 = BboxConnector(inset_axes.bbox, rect, loc1=loc1, **kwargs)
      inset_axes.add_patch(p1)
      p1.set_clip_on(False)
      p2 = BboxConnector(inset_axes.bbox, rect, loc1=loc2, **kwargs)
      inset_axes.add_patch(p2)
      p2.set_clip_on(False)
  
      return pp, p1, p2
  
imports: from __future__ import absolute_import, division, print_function, unicode_literals
  import warnings
  from matplotlib import docstring
  import six
  from matplotlib.offsetbox import AnchoredOffsetbox
  from matplotlib.patches import Patch, Rectangle
  from matplotlib.path import Path
  from matplotlib.transforms import Bbox, BboxTransformTo
  from matplotlib.transforms import IdentityTransform, TransformedBbox
  from .None import axes_size
  from .parasite_axes import HostAxes
label_desc: Use image node_id 4 for calling a global function with example usage: mark_inset(parent_axes, inset_axes, loc1, loc2) and returns: pp,  p1,  p2