promql/functions.go
func funcIrate(vals []Value, args Expressions, enh *EvalNodeHelper) Vector {
	return instantValue(vals, enh.out, true)
}
func funcIrate(vals []Value, args Expressions, enh *EvalNodeHelper) Vector {
	return instantValue(vals, enh.out, true)
}
// === irate(node ValueTypeMatrix) Vector ===