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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 get_shortlink(self, shortlink_id_or_url):
 """Retrieve registered shortlink info Arguments: shortlink_id_or_url: Shortlink id or url, assigned by mCASH """

        if "://" not in shortlink_id_or_url:
            shortlink_id_or_url = self.merchant_api_base_url + '/shortlink/' + shortlink_id_or_url + '/'

        return self.do_req('GET', shortlink_id_or_url).json()