def remove_redefineds(self, redefineds):
        """Take a set of variables in redefineds and go through all
        the currently existing equivalence sets (created in topo order)
        and remove that variable from all of them since it is multiply
        defined within the function.
        """
        unused = set()
        for r in redefineds:
            for eslabel in self.equiv_sets:
                es = self.equiv_sets[eslabel]
                es.define(r, unused)
Take a set of variables in redefineds and go through all
        the currently existing equivalence sets (created in topo order)
        and remove that variable from all of them since it is multiply
        defined within the function.
        
numba/parfors/array_analysis.py