Send the start of a data fragment stream to a websocket client.
            Subsequent data should be sent using sendFragment().
            A fragment stream is completed when sendFragmentEnd() is called.

            If data is a unicode object then the frame is sent as Text.
            If the data is a bytearray object then the frame is sent as Binary.

def sendFragmentStart(self, data):
        """
            Send the start of a data fragment stream to a websocket client.
            Subsequent data should be sent using sendFragment().
            A fragment stream is completed when sendFragmentEnd() is called.

            If data is a unicode object then the frame is sent as Text.
            If the data is a bytearray object then the frame is sent as Binary.
        """
        opcode = BINARY
        if _check_unicode(data):
            opcode = TEXT
        self._sendMessage(True, opcode, data)