code: func funcDaysInMonth(vals []Value, args Expressions, enh *EvalNodeHelper) Vector {
  	return dateWrapper(vals, enh, func(t time.Time) float64 {
  		return float64(32 - time.Date(t.Year(), t.Month(), 32, 0, 0, 0, 0, time.UTC).Day())
  	})
  }
docs: // === days_in_month(v Vector) Scalar ===