promql/functions.go
func funcAbs(vals []Value, args Expressions, enh *EvalNodeHelper) Vector {
	return simpleFunc(vals, enh, math.Abs)
}
func funcAbs(vals []Value, args Expressions, enh *EvalNodeHelper) Vector {
	return simpleFunc(vals, enh, math.Abs)
}
// === abs(Vector ValueTypeVector) Vector ===