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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 environment, as available. """

        result = {
            'username': response[self.ENV_USERNAME],
            'email': response.get(self.ENV_EMAIL, None),
            'first_name': response.get(self.ENV_FIRST_NAME, None),
            'last_name': response.get(self.ENV_LAST_NAME, None)
        }
        if result['first_name'] and result['last_name']:
            result['fullname']=result['first_name']+' '+result['last_name']
        logger.debug("Returning user details: "+str(result))
        return result