code: def bytes_needed(self):
              '''return number of bytes needed for next parsing stage'''
              if self.native:
                  ret = self.native.expected_length - self.buf_len()
              else:
                  ret = self.expected_length - self.buf_len()
              
              if ret <= 0:
                  return 1
              return ref bytes_needed(self):
              '''return number of bytes needed for next parsing stage'''
              if self.native:
                  ret = self.native.expected_length - self.buf_len()
              else:
                  ret = self.expected_length - self.buf_len()
              
              if ret <= 0:
                  return 1
              return ret
docs: return number of bytes needed for next parsing stage