The FARFALLA package defines several functions which are members of the class F_Node. All node classes which you define inherit from F_Node so they also have these functions available. Member functions are invoked by preceding the function with a pointer to a node; i.e. the member function returnType() might be invoked like this:
erpPtr->returnType();
Most member functions operate on data in the node; thus, calling the
same function for different nodes will give different results.
Suppose the tree shown in Figure 
exists in memory.
(Here, a node of extended erp data has been hung off an existing
standard erp node.) If erpPtr1 points at the left erp child and
erpPtr2 points at the right erp child, then
erpPtr1->numChildren(extendedErpType) would return 0, while
erpPtr2->numChildren(extendedErpType) would return 1.
