docs: def get_children(self):
          """Return tiles from next zoom level."""
          next_zoom = self.zoom + 1
          return [
              self.tile_pyramid.tile(
                  next_zoom,
                  self.row * 2 + row_offset,
                  self.col * 2 + col_offset
              )
              for row_offset, col_offset in [
                  (0, 0),  # top left
                  (0, 1),  # top right
                  (1, 1),  # bottom right
                  (1, 0),  # bottom left
              ]
              if all([
                  self.row * 2 + row_offset < self.tp.matrix_height(next_zoom),
                  self.col * 2 + col_offset < self.tp.matrix_width(next_zoom)
              ])
          ]