def update_security_policy(self, policy_id, new_policy, new_policy_type,
                               new_grantee):
        '''
        Updates an existing security policy based on the inputs specified
        by the user.
        '''
        query = ('UPDATE dh_public.policy '
                 'SET policy = %s, policy_type = %s, '
                 'grantee = %s '
                 'WHERE policy_id = %s')
        params = (new_policy, new_policy_type, new_grantee, policy_id)

        res = self.execute_sql(query, params)
        return res['status']