code: def read_until(self, s, echo=None):
          
  
          s_len = len(s)
          buf = self.read(s_len, echo)
  
          while buf[-s_len:] != s:
              buf += self.read(1, echo)
  
          return buf
docs: Read until a certain string is encountered..
  
          Args:
              s(bytes): The string to wait for.
              echo(bool): Whether to write the read data to stdout.
  
          Returns:
              bytes: The data up to and including *s*.
  
          Raises:
              EOFError: If the channel was closed.