def register(self, username=""):
        """Performs /register with type: m.login.application_service

        Args:
            username(str): Username to register.
        """
        if not username:
            username = utils.mxid2localpart(self.identity)
        content = {
            "type": "m.login.application_service",
            "username": username,
        }
        return self._send("POST", "/register", content,
                          api_path=MATRIX_V2_API_PATH)
Performs /register with type: m.login.application_service

        Args:
            username(str): Username to register.