code: def _detect_multi_byte(self, fb):
          # type: (str) -> bool
          
          assert(isinstance(fb, int) or len(fb) == 1)
          return (orb(fb) & self._max_value) == self._max_value
docs: _detect_multi_byte returns whether the AbstractUVarIntField is represented on  # noqa: E501
            multiple bytes or not.
  
            A multibyte representation is indicated by all of the first size bits being set  # noqa: E501
  
          @param str fb: first byte, as a character.
          @return bool: True if multibyte repr detected, else False.
          @raise AssertionError