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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_user_details(self, response):
 """ Complete with additional information from original LTI POST data, as available. """

        data = {}
        # None of them is mandatory
        data['id'] = response.get('user_id', None)
        data['username'] = response.get('custom_username', None)
        if not data['username']:
            data['username'] = response.get('ext_user_username', None)
        data['last_name'] = response.get('lis_person_name_family', None)
        data['email'] = response.get(
            'lis_person_contact_email_primary', None)
        data['first_name'] = response.get('lis_person_name_given', None)
        data['fullname'] = response.get('lis_person_name_full', None)
        logger.debug("User details being used: " + str(data))
        return data