message.py

class Twilio(object):

    def send(self, message, to):
        print "SMS '" + message + "' sent to " + to


class Email(object):

    def send(self, message, to):
        print "Email '" + message + "' sent to " + to


class SmsDevice(object):

    def __init__(self, phone_number):

        self.phone_number = phone_number


class EmailDevice(object):

    def __init__(self, email_address):

        self.email_address = email_address


class Message(object):

    def __init__(self, body):

        self.body = body

    def send_to(self, recipients):

        for recipient in recipients:

            if isinstance(recipient, SmsDevice):
                self.send_sms(self.body, recipient.phone_number)

            elif isinstance(recipient, EmailDevice):
                self.send_email(self.body, recipient.email_address)

    def send_sms(self, message, phone_number):

        Twilio().send(message, phone_number)

    def send_email(self, message, email):

        Email().send(message, email)


if __name__ == '__main__':

    message = Message("Hello, world!")
    recipients = [
        SmsDevice('+1-555-555-1212'),
        EmailDevice('user@example.com'),
    ]

    message.send_to(recipients)