'send message.
data: message to send. If you set opcode to OPCODE_TEXT,
data must be utf-8 string or unicode.
opcode: operation code of data. default is OPCODE_TEXT.'

def send(self, data, opcode=ABNF.OPCODE_TEXT):

    if ((not self.sock) or (self.sock.send(data, opcode) == 0)):
        raise WebSocketConnectionClosedException('Connection    is    already    closed.')
