An MFG (Method Flow Graph) is a directed graph, which
represents the caller-callee relations of methods in a single
class1. An MFG node denotes the definition of each
method, and when method A possibly calls method B, an
MFG edge is drawn from the node for A to the node for B.
Fig.8 shows a sample program and its MFG. Method
p() is not defined in class B, and method A::p() is executed
when p() is activated on B’s object. In this case,
method call to q() appearing in A::p() causes activation