promql/functions.go
func funcLog2(vals []Value, args Expressions, enh *EvalNodeHelper) Vector {
	return simpleFunc(vals, enh, math.Log2)
}
func funcLog2(vals []Value, args Expressions, enh *EvalNodeHelper) Vector {
	return simpleFunc(vals, enh, math.Log2)
}
// === log2(Vector ValueTypeVector) Vector ===