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// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package maps
// Group returns a new non-nil map containing the elements of s grouped by the
// keys returned from the key func.
func Group[K comparable, V any](s []V, key func(V) K) map[K][]V {
m := make(map[K][]V)
for _, v := range s {
k := key(v)
m[k] = append(m[k], v)
}
return m
}
// Keys returns the keys of the map M.
func Keys[M ~map[K]V, K comparable, V any](m M) []K {
r := make([]K, 0, len(m))
for k := range m {
r = append(r, k)
}
return r
}
// SameKeys reports whether x and y have equal sets of keys.
func SameKeys[K comparable, V1, V2 any](x map[K]V1, y map[K]V2) bool {
if len(x) != len(y) {
return false
}
for k := range x {
if _, ok := y[k]; !ok {
return false
}
}
return true
}
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