ine?</p><p><span class="underline">Answer</span>: Usually you'll want to implement the
                state machine as an attribute of the class. Unfortunately, a concrete state machine
                is a typedef, which cannot be forward-declared. This leaves you with two
                possibilities: </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>Provide the state machine definition inside the header class and
                            contain an instance a