void addCall(final MethodEditor callerMethod, final MemberRef callee) {
		// Just maintain the calls mapping
		final MemberRef caller = callerMethod.memberRef();
		Set callees = (Set) this.calls.get(caller);
		if (callees == null) {
			callees = new HashSet();
			this.calls.put(caller, callees);
		}
		callees.add(callee);
	}