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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def send_messages(self, sms_messages):
 """ Sends one or more SmsMessage objects and returns the number of sms messages sent. """

        if not sms_messages:
            return
        
        num_sent = 0
        for message in sms_messages:
            if self._send(message):
                num_sent += 1
        return num_sent