Implement a class Address. An address has a house number, a street, an optional apartment number, a city, a state, and a postal code. Supply two constructors: one with an apartment number and one without.
Supply a print function that prints the address with the street on one line and the city, state, and postal code on the next line.
Supply a member function comes_before that tests whether one address comes before another when the addresses are compared by postal code.