promql/functions.go
func funcTimestamp(vals []Value, args Expressions, enh *EvalNodeHelper) Vector {
	vec := vals[0].(Vector)
	for _, el := range vec {
		enh.out = append(enh.out, Sample{
			Metric: enh.dropMetricName(el.Metric),
			Point:  Point{V: float64(el.T) / 1000},
		})
	}
	return enh.out
}
func funcTimestamp(vals []Value, args Expressions, enh *EvalNodeHelper) Vector {
	vec := vals[0].(Vector)
	for _, el := range vec {
		enh.out = append(enh.out, Sample{
			Metric: enh.dropMetricName(el.Metric),
			Point:  Point{V: float64(el.T) / 1000},
		})
	}
	return enh.out
}
// === timestamp(Vector ValueTypeVector) Vector ===