'Kill previous defs. addr_list is a list of normalized addresses.'

def _kill(self, live_defs, variable, code_loc):

    if (variable in live_defs):
        for loc in live_defs.lookup_defs(variable):
            pv = ProgramVariable(variable, loc)
            self._data_graph_add_edge(pv, ProgramVariable(variable, code_loc), type='kill')
    live_defs.kill_def(variable, code_loc)
