'Returns the get HTTP response by doing a POST to /synthesize with
text, voice, accept'

def synthesize(self, text, voice=None, accept=None, customization_id=None):

    params = {'voice': voice, 'accept': accept, 'customization_id': customization_id}
    data = {'text': text}
    response = self.request(method='POST', url='/v1/synthesize', stream=True, params=params, json=data)
    return response.content
