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.
For second and subsequent pregnancies, women often start showing sooner than during the first pregnancy. There are also some women do not look noticeably pregnant until they are into their third trimester. Early in pregnancy, you may be more vigilant in looking for changes. You may think you look pregnant more at the end of the day when you've eaten dinner and your muscles are more relaxed. You may have bloating or constipation that you didn't have before pregnancy that contributes to this. However, your uterus won't have expanded above your pelvis enough to be the cause of the bump until the second trimester. Changes in the first trimester often do not mean you need maternity clothes just yet.