(b)any person, authorized or empowered by or under this Act or with whom the municipality or any of the municipal authorities has lawfully entered into a contract, in the performance of his or its duty, or in the execution of his or its work, or anything which he or it is empowered or required to do by virtue, or in consequence, of any provision of this Act or the rules or the regulations made thereunder, or in the fulfillment of the contract, as the case may be.
