docs: def copy(self):
          """
          Return a copy of this ProtoFeed, that is, a feed with all the
          same attributes.
          """
          other = ProtoFeed()
          for key in cs.PROTOFEED_ATTRS:
              value = getattr(self, key)
              if isinstance(value, pd.DataFrame):
                  # Pandas copy DataFrame
                  value = value.copy()
              setattr(other, key, value)
  
          return other