code: def load(cls, filename, format=None):
          
          if format is None:
              # try to derive protocol from file extension
              format = format_from_extension(filename)
          with file(filename, 'rbU') as fp:
              obj = cls.load_from_file_object(fp, format)
              obj.filename = filename
              return obj
docs: Return an instance of the class that is saved in the file with the
              given filename in the specified format.