code: def get_ehlo_lines(self):
          
          lines = []
          if self._authenticator != None:
              # TODO: Make the authentication pluggable but separate mechanism
              # from user look-up.
              lines.append('AUTH PLAIN')
          if self._policy != None:
              lines.extend(self._policy.ehlo_lines(self._message.peer))
          lines.append('HELP')
          return lines
docs: Return the capabilities to be advertised after EHLO.