schema: schemas(durationFormat, durationFormat),
			expectCost: map[string]int64{
				ValsEqualThemselvesAndDataLiteral("self.val1", "self.val2", "duration('1h2m3s4ms')"): 11,
				"self.val1 == duration('1h2m') + duration('3s4ms')":                                  4,
				"self.val1.getHours() == 1":                                                          4,

			schema: schemas(durationFormat, durationFormat),
			valid: []string{
				ValsEqualThemselvesAndDataLiteral("self.val1", "self.val2", "duration('1h2m3s4ms')"),
				"self.val1 == duration('1h2m') + duration('3s4ms')",
				"self.val1.getHours() == 1",
				"self.val1.getMinutes() == 62",
				"self.val1.getSeconds() == 3723",
				"self.val1.getMilliseconds() == 3723004",

			h2 := tt.new()
			h3 := tt.new()
			const split = 249
			for i := 0; i < split; i++ {
				h2.Write(buf[i : i+1])
			}
			h2m, ok := h2.(encoding.BinaryMarshaler)
			if !ok {
				t.Fatalf("Hash does not implement MarshalBinary")
			}
			enc, err := h2m.MarshalBinary()
			if err != nil {
				t.Fatalf("MarshalBinary: %v", err)
			}
			if !bytes.Equal(enc, tt.golden) {

        "1 hour"            | "10 hours"          | hours(1)                            | "1h"
        "1 hour"            | "10 hours"          | hours(4.2123456)                    | "4h 12m 44s"
        "10 hours"          | "100 hours"         | hours(42.123456)                    | "42h 7m 24s"
        "100 hours"         | "None"              | hours(421.23456)                    | "421h 14m 4s"

	// d.Round( 10m0s) = 1h20m0s
	// d.Round(1h0m0s) = 1h0m0s
}

func ExampleDuration_String() {
	fmt.Println(1*time.Hour + 2*time.Minute + 300*time.Millisecond)
	fmt.Println(300 * time.Millisecond)
	// Output:
	// 1h2m0.3s
	// 300ms
}

func ExampleDuration_Truncate() {
	d, err := time.ParseDuration("1h15m30.918273645s")
	if err != nil {
		panic(err)
	}

	trunc := []time.Duration{
		time.Nanosecond,

type Format string

const (
	DecimalExponent = Format("DecimalExponent") // e.g., 12e6
	BinarySI        = Format("BinarySI")        // e.g., 12Mi (12 * 2^20)
	DecimalSI       = Format("DecimalSI")       // e.g., 12M  (12 * 10^6)
)

// MustParse turns the given string into a quantity or panics; for tests
// or other cases where you know the string is valid.
func MustParse(str string) Quantity {
	q, err := ParseQuantity(str)