def eval_unx(self, exp):
    "unary expressions"
    inner=self.eval(exp.val)
    if exp.op.op=='+': return inner
    elif exp.op.op=='-': return -inner
    elif exp.op.op=='not': return threevl.ThreeVL.nein(inner)
    else: raise NotImplementedError('unk_op',exp.op)
def eval_unx ( self , exp ) : inner = self . eval ( exp . val ) if exp . op . op == '+' : return inner elif exp . op . op == '-' : return - inner elif exp . op . op == 'not' : return threevl . ThreeVL . nein ( inner ) else : raise NotImplementedError ( 'unk_op' , exp . op )
unary expressions