legislative contract regarding taxation

the legislature of a state may, in the absence of special restrictions in its Constitution, make a valid contract with a corporation in respect to taxation, and that such contract can be enforced against the state at the instance of the corporation. ... [W]e accept the ruling that the statutes are valid and applicable enactments. ... the supreme court of the state having sustained the validity of a statute from which a contract is claimed, this court follows that decision, and starts with the question, What contract is shown by statute?