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 some women, early signs and symptoms of pregnancy begin in the first few weeks after conception. However, it is possible you may not experience any symptoms for a few weeks. I would suggest you to wait for a few days until your period is showing up or to take a pregnancy test.