Make tables congruent.
Makes tables congruent by ensuring they have the same variables of the same types in the same order. Congruent tables may be safely unioned, intersected, vertcatted, or have other set operations done to them.
Variable names present in one input but not in the other produces an error. Variables with the same name but different types in the inputs produces an error. Inputs must either both have row names or both not have row names; it is an error if one has row names and the other doesn’t. Variables in different orders are reordered to be in the same order as A.