How to use the persim.images.PersImage.to_landscape function in persim

"""
        # if diagram is empty, return empty image
        if len(diagrams) == 0:
            return np.zeros((self.nx, self.ny))
        # if first entry of first entry is not iterable, then diagrams is singular and we need to make it a list of diagrams
        try:
            singular = not isinstance(diagrams[0][0], collections.Iterable)
        except IndexError:
            singular = False

        if singular:
            diagrams = [diagrams]

        dgs = [np.copy(diagram) for diagram in diagrams]
        landscapes = [PersImage.to_landscape(dg) for dg in dgs]

        if not self.specs:
            self.specs = {
                "maxBD": np.max([np.max(np.vstack((landscape, np.zeros((1, 2))))) 
                                 for landscape in landscapes] + [0]),
                "minBD": np.min([np.min(np.vstack((landscape, np.zeros((1, 2))))) 
                                 for landscape in landscapes] + [0]),
            }
        imgs = [self._transform(dgm) for dgm in landscapes]

        # Make sure we return one item.
        if singular:
            imgs = imgs[0]

        return imgs