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

def add_axes_at_origin(self, loc=None):
        """
        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
        """
        self._active_renderer_index = self.loc_to_index(loc)
        return self.renderers[self._active_renderer_index].add_axes_at_origin()