'Create an authenticator. You can supply consumer_key and
consumer_secret if you are requesting a bearer_token. Otherwise
you must supply the bearer_token.'

def __init__(self, consumer_key=None, consumer_secret=None, bearer_token=None):

    self.bearer_token = bearer_token
    self.consumer_key = consumer_key
    self.consumer_secret = consumer_secret
    if (not (bearer_token or (consumer_key and consumer_secret))):
        raise MissingCredentialsError('You    must    supply    either    a    bearer    token,    or    both    a    consumer_key    and    a    consumer_secret.')
