code: def explain_validity(ob):
      """
      Explain the validity of the input geometry, if it is invalid.
      This will describe why the geometry is invalid, and might
      include a location if there is a self-intersection or a
      ring self-intersection.
  
      Parameters
      ----------
      ob: Geometry
          A shapely geometry object
  
      Returns
      -------
      str
          A string describing the reason the geometry is invalid.
  
      """
      return shapely.is_valid_reason(ob)
  
label_desc: Use image node_id 1 for calling a global function with example usage: explain_validity(ob) and returns: shapely