Attaches the policy to the user

def _attach_inline_policy(self, username, policy_document):
        """Attaches the policy to the user"""
        response = self.client.put_user_policy(
            UserName=username,
            PolicyName="threatresponse-temporal-key-revocation",
            PolicyDocument=policy_document
        )
        logger.info(
            'An inline policy has been attached for'
            ' {u} revoking sts tokens.'.format(u=username)
        )
        return response