type _ interface {
	int
	[]byte
	[10]int
	struct{}
	*int
	func()
	interface{}
	map[string]int
	chan T
	chan<- T
	<-chan T
	T[int]
}

type _ interface {
	int | string
	[]byte | string
	[10]int | string
	struct{} | string
	*int | string
	func() | string
	interface{} | string
	map[string]int | string
	chan T | string
	chan<- T | string
	<-chan T | string
	T[int] | string
}

	}
}

func TestMapType(t *testing.T) {
	var m map[string]int
	mapStringInt := getTypeUnlocked("map", reflect.TypeOf(m))
	var newm map[string]int
	newMapStringInt := getTypeUnlocked("map1", reflect.TypeOf(newm))
	if mapStringInt != newMapStringInt {
		t.Errorf("second registration of map[string]int creates new type")
	}
	var b map[string]bool
	mapStringBool := getTypeUnlocked("", reflect.TypeOf(b))

}

var (
	mu          sync.Mutex
	crawled     = make(map[string]bool)      // URL without fragment -> true
	neededFrags = make(map[urlFrag][]string) // URL#frag -> who needs it
)

var aRx = regexp.MustCompile(`<a href=['"]?(/[^\s'">]+)`)

// Owned by crawlLoop goroutine:
var (
	linkSources = make(map[string][]string) // url no fragment -> sources
	fragExists  = make(map[urlFrag]bool)
	problems    []string
)

	"sync"
)

var (
	mimeTypes      sync.Map // map[string]string; ".Z" => "application/x-compress"
	mimeTypesLower sync.Map // map[string]string; ".z" => "application/x-compress"

	// extensions maps from MIME type to list of lowercase file
	// extensions: "image/jpeg" => [".jpg", ".jpeg"]
	extensionsMu sync.Mutex // Guards stores (but not loads) on extensions.
	extensions   sync.Map   // map[string][]string; slice values are append-only.
)

package main

type T struct {
	m map[int]int
}

func main() {
	t := T{
		m: make(map[int]int),
	}
	t.Inc(5)
	t.Inc(7)
}

func (s *T) Inc(key int) {
	v := s.m[key] // break, line 16
	v++
	s.m[key] = v // also here

// See the comment on the declaration of makeFuncStub in makefunc.go
// for more details.
// No arg size here, runtime pulls arg map out of the func value.
TEXT ·makeFuncStub(SB),(NOSPLIT|WRAPPER),$336
	NO_LOCAL_POINTERS
	// NO_LOCAL_POINTERS is a lie. The stack map for the two locals in this
	// frame is specially handled in the runtime. See the comment above LOCAL_RETVALID.
	ADD	$LOCAL_REGARGS, R1, R20

	multipartmaxparts = godebug.New("multipartmaxparts")
)

func (r *Reader) readForm(maxMemory int64) (_ *Form, err error) {
	form := &Form{make(map[string][]string), make(map[string][]*FileHeader)}
	var (
		file    *os.File
		fileOff int64
	)
	numDiskFiles := 0
	combineFiles := true
	if multipartfiles.Value() == "distinct" {
		combineFiles = false

	ELSE:        "else",
	FALLTHROUGH: "fallthrough",
	FOR:         "for",

	FUNC:   "func",
	GO:     "go",
	GOTO:   "goto",
	IF:     "if",
	IMPORT: "import",

	INTERFACE: "interface",
	MAP:       "map",
	PACKAGE:   "package",
	RANGE:     "range",
	RETURN:    "return",

	SELECT: "select",
	STRUCT: "struct",
	SWITCH: "switch",
	TYPE:   "type",
	VAR:    "var",

	TILDE: "~",
}

func TestMap() {
	s1 := []int{1, 2, 3}
	s2 := a.Map(s1, func(i int) float64 { return float64(i) * 2.5 })
	if want := []float64{2.5, 5, 7.5}; !a.Equal(s2, want) {
		panic(fmt.Sprintf("a.Map(%v, ...) = %v, want %v", s1, s2, want))
	}

	s3 := []string{"Hello", "World"}
	s4 := a.Map(s3, strings.ToLower)
	if want := []string{"hello", "world"}; !a.Equal(s4, want) {
		panic(fmt.Sprintf("a.Map(%v, strings.ToLower) = %v, want %v", s3, s4, want))
	}

-- input --
We use [io.Reader] a lot, and also a few map[io.Reader]string.

Never [io.Reader]int or Slice[io.Reader] though.
-- markdown --
We use [io.Reader](/io#Reader) a lot, and also a few map\[io.Reader]string.