code: def readline(self, size=None):
          
          if size is not None:
              data = self.rfile.readline(size)
              self.bytes_read += len(data)
              self._check_length()
              return data
  
          # User didn't specify a size ...
          # We read the line in chunks to make sure it's not a 100MB line !
          res = []
          while True:
              data = self.rfile.readline(256)
              self.bytes_read += len(data)
              self._check_length()
              res.append(data)
              # See https://github.com/cherrypy/cherrypy/issues/421
              if len(data) < 256 or data[-1:] == LF:
                  return EMPTY.join(res)
docs: Read a single line from rfile buffer and return it.
  
          Args:
              size (int): minimum amount of data to read
  
          Returns:
              bytes: One line from rfile.