In instantiating the ImmutableString, the function pointers to the get and length methods actually refer to the String.get and String.length method, by going through the base variable which is an internally stored String object. The use of a function pointer can achieve inheritance of a method from a superclass.
Most women will start to show at some point between weeks 12 and 24 of pregnancy, with most reporting that they began to show during the first half of their second trimester, between 12 and 18 weeks.
On average, women start to show around the fourth month of pregnancy, between weeks 14 and 17. By week 17 the uterus usually has expanded to just an inch and a half below the navel, making the pregnancy more obvious.