}
	b1.Flush()
	if w1 != 3 {
		t.Fatalf("flush 1200 + 1389 'x's: got %d writes, want 3", w1)
	}
}

// A writeCountingDiscard is like io.Discard and counts the number of times
// Write is called on it.
type writeCountingDiscard int

func (w *writeCountingDiscard) Write(p []byte) (int, error) {
	*w++
	return len(p), nil
}

type negativeReader int

// The opening parenthesis has been absorbed.
func (in *Input) argsFor(macro *Macro) map[string][]Token {
	var args [][]Token
	// One macro argument per iteration. Collect them all and check counts afterwards.
	for argNum := 0; ; argNum++ {
		tokens, tok := in.collectArgument(macro)
		args = append(args, tokens)
		if tok == ')' {
			break
		}
	}
	// Zero-argument macros are tricky.

	na := 0
	for len(s) > 0 {
		if na+1 >= n {
			a[na] = s
			na++
			break
		}
		_, size = utf8.DecodeRune(s)
		a[na] = s[0:size:size]
		s = s[size:]
		na++
	}
	return a[0:na]
}

// Count counts the number of non-overlapping instances of sep in s.
// If sep is an empty slice, Count returns 1 + the number of UTF-8-encoded code points in s.
func Count(s, sep []byte) int {
	// special case
	if len(sep) == 0 {

[runtime/metrics](/pkg/runtime/metrics/) counter
named `/godebug/non-default-behavior/<name>:events`
that counts the number of times a particular program's
behavior has changed based on a non-default value
for that setting.
For example, when `GODEBUG=http2client=0` is set,
`/godebug/non-default-behavior/http2client:events`
counts the number of HTTP transports that the program
has configured without HTTP/2 support.

pkg runtime/metrics, type Description struct, Name string
pkg runtime/metrics, type Float64Histogram struct
pkg runtime/metrics, type Float64Histogram struct, Buckets []float64
pkg runtime/metrics, type Float64Histogram struct, Counts []uint64
pkg runtime/metrics, type Sample struct
pkg runtime/metrics, type Sample struct, Name string
pkg runtime/metrics, type Sample struct, Value Value
pkg runtime/metrics, type Value struct