code: def handle_read_fast_case(self, data):
          
          if self.state is not STATE_RUNNING or callbacks.any_in(data):
              # Slow case :-(
              return False
  
          last_nl = data.rfind(b'\n')
          if last_nl == -1:
              # No '\n' in data => slow case
              return False
          self.read_buffer = data[last_nl + 1:]
          self.print_lines(data[:last_nl])
          return True
docs: If we are in a fast case we'll avoid the long processing of each
          line