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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 friendships_create(self, user_id=None, screen_name=None, follow=None):
 """ Allows the authenticating users to follow the specified user. https://dev.twitter.com/docs/api/1.1/post/friendships/create :param str user_id: The screen name of the user for whom to befriend. Required if ``screen_name`` isn't given. :param str screen_name: The ID of the user for whom to befriend. Required if ``user_id`` isn't given. :param bool follow: Enable notifications for the target user. :returns: A dict containing the newly followed user. """

        params = {}
        set_str_param(params, 'user_id', user_id)
        set_str_param(params, 'screen_name', screen_name)
        set_bool_param(params, 'follow', follow)
        return self._post_api('friendships/create.json', params)