问在twisted中，我如何创建一个基于输入返回Lines或Raw的混合协议？

EN

class Receiver(LineReceiver):
def lineReceived(self, line):
    (command, args) = self._parse_command(line)
    result = self.exec_command(command, args) #Secret sauce returns list or blob.
    if  isinstance(result, basestring): # won't work in 3.0 ; least of my worries.
        self.sendLine(str(len(result))) # Sends no. of bytes as a line.
        self.transport.write(result)   #followed by bytes. This is not received by the client.
        self.transport.loseConnection()
    else:
        no_lines = len(result)
        self.sendLine(str(no_lines)) 
        for r in result:
            self.sendLine(str(r))