'Validate the edges.'

def validate(self):

    for function in self.functions.itervalues():
        for callee_id in function.calls.keys():
            assert (function.calls[callee_id].callee_id == callee_id)
            if (callee_id not in self.functions):
                sys.stderr.write(('warning:    call    to    undefined    function    %s    from    function    %s\n' % (str(callee_id), function.name)))
                del function.calls[callee_id]
