Of course, it is fundamental that, in proceedings like this, municipalities can act legally only in strict compliance with the requirements of the statutory law, defining their activities, or to put it in the language of the decisions, that the mode is the measure of their power. In the case of City of Napa v. Maxwell, 36 Cal.App. 103, [171 P. 839], the court uses the following language: "Of course, the rule is that proceedings for the improvement of streets are in invitum and purely statutory, and afford no opportunity for invoking any of the principles of equity, and the validity of an assessment, therefore, depends upon a statutory power, and the party seeking the right to enforce it must show that the statutory power has been strictly followed." Therein, the proceedings were declared invalid because two commissioners, instead of three, were appointed as provided for by section 6 of the act of 1889, to ascertain the benefits accruing or the damage resulting to property affected by the proposed improvement.