code: 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
  }
docs: // === timestamp(Vector ValueTypeVector) Vector ===