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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 watson_request(text, synth_args):
 """ Makes a single request to the IBM Watson text-to-speech API. :param text: The text that will be synthesized to audio. :param synth_args: A dictionary of arguments to add to the request. These should include username and password for authentication. """

    params = {
        'text': text,
        'accept': 'audio/wav'
    }
    if synth_args is not None:
        params.update(synth_args)

    if 'username' in params:
        username = params.pop('username')
    else:
        raise Warning('The IBM Watson API requires credentials that should be passed as "username" and "password" in "synth_args"')
    if 'password' in params:
        password = params.pop('password')
    else:
        raise Warning('The IBM Watson API requires credentials that should be passed as "username" and "password" in "synth_args"')

    return requests.get(watson_url, auth=(username, password), params=params)