second class when the performance of one condition is not obligatory until the actual performance of the other; and to the third class when neither party need perform his con-dition unless the other is ready and willing to perform his, or, in other words, when the mu-tual covenants go to the whole consideration on both sides and each is precedent to the oth-er. Huggins v. Daley, 99 Fed. 609, 40 C. C. A. 12, 48 L. R. A. 320
