code: def read_little_endian64(self):
          
          try:
              i = struct.unpack(wire_format.FORMAT_UINT64_LITTLE_ENDIAN,
                                self._input.read(8))
              self._pos += 8
              return i[0]  # unpack() result is a 1-element tuple.
          except struct.error as e:
              raise errors.DecodeError(e)
docs: Interprets the next 8 bytes of the stream as a little-endian
          encoded, unsiged 64-bit integer, and returns that integer.