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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 add_auth(f):
 """A decorator that adds the authentication header to requests arguments"""


    def add_auth_decorator(*args, **kwargs):
        token = get_user_token()
        if 'headers' not in kwargs:
            kwargs['headers'] = {}
        kwargs['headers']['Authorization'] = "Bearer %s" % token
        return f(*args, **kwargs)

    return add_auth_decorator