code: def add_axes_at_origin(self, loc=None):
          
          self._active_renderer_index = self.loc_to_index(loc)
          return self.renderers[self._active_renderer_index].add_axes_at_origin()
docs: Add axes actor at the origin of a render window.
  
          Parameters
          ----------
          loc : int, tuple, or list
              Index of the renderer to add the actor to.  For example,
              ``loc=2`` or ``loc=(1, 1)``.  When None, defaults to the
              active render window.
  
          Returns
          --------
          marker_actor : vtk.vtkAxesActor
              vtkAxesActor actor