examples/research_projects/lxmert/modeling_frcnn.py/AnchorGenerator/num_cell_anchors
class AnchorGenerator:    def num_cell_anchors(self):
        """
        Returns:
            list[int]: Each int is the number of anchors at every pixel location, on that feature map.
        """
        return [len(cell_anchors) for cell_anchors in self.cell_anchors]