code: def _to_tuple(bbox):
          
          if isinstance(bbox, (list, tuple)):
              return BBox._tuple_from_list_or_tuple(bbox)
          if isinstance(bbox, str):
              return BBox._tuple_from_str(bbox)
          if isinstance(bbox, dict):
              return BBox._tuple_from_dict(bbox)
          if isinstance(bbox, BBox):
              return BBox._tuple_from_bbox(bbox)
          if isinstance(bbox, shapely.geometry.base.BaseGeometry):
              return bbox.bounds
          raise TypeError('Invalid bbox representation')
docs: Converts the input bbox representation (see the constructor docstring for a list of valid representations)
          into a flat tuple
  
          :param bbox: A bbox in one of 7 forms listed in the class description.
          :return: A flat tuple of size
          :raises: TypeError