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.
Some women do not start to show until they are well into their second trimester or even the start of their third trimester. If you are overweight at the start of your pregnancy, you may not gain as much weight during your pregnancy and may not begin to show until later into your pregnancy.