nWhen we use the statement member function with our account pointer, the actual member function used is the account's statement member function.
nThis is because static binding is in effect.
nThe member function bound
by the compiler is based on
the static type of the pointer, not the actual or dynamic type of the object pointed to.
nThus, even though the
complete derived class object is there,
static binding prevents us from using the derived class' statement member function.