def undef(cls, loc):
        """
        A node for undefined value specifically from LOAD_FAST_AND_CLEAR opcode.
        """
        assert isinstance(loc, Loc)
        op = 'undef'
        return cls(op=op, loc=loc)

        A node for undefined value specifically from LOAD_FAST_AND_CLEAR opcode.
        
numba/core/ir.py