doc: add go playground demo

maputil/map.go

@@ -39,7 +39,7 @@ func Values[K comparable, V any](m map[K]V) []V {
 }
 
 // KeysBy creates a slice whose element is the result of function mapper invoked by every map's key.
-// Play: todo
+// Play: https://go.dev/play/p/hI371iB8Up8
 func KeysBy[K comparable, V any, T any](m map[K]V, mapper func(item K) T) []T {
 	keys := make([]T, 0, len(m))
 
@@ -51,7 +51,7 @@ func KeysBy[K comparable, V any, T any](m map[K]V, mapper func(item K) T) []T {
 }
 
 // ValuesBy creates a slice whose element is the result of function mapper invoked by every map's value.
-// Play: todo
+// Play: https://go.dev/play/p/sg9-oRidh8f
 func ValuesBy[K comparable, V any, T any](m map[K]V, mapper func(item V) T) []T {
 	keys := make([]T, 0, len(m))
 
@@ -98,7 +98,7 @@ func Filter[K comparable, V any](m map[K]V, predicate func(key K, value V) bool)
 }
 
 // FilterByKeys iterates over map, return a new map whose keys are all given keys.
-// Play: todo
+// Play: https://go.dev/play/p/7ov6BJHbVqh
 func FilterByKeys[K comparable, V any](m map[K]V, keys []K) map[K]V {
 	result := make(map[K]V)
 
@@ -111,7 +111,7 @@ func FilterByKeys[K comparable, V any](m map[K]V, keys []K) map[K]V {
 }
 
 // FilterByValues iterates over map, return a new map whose values are all given values.
-// Play: todo
+// Play: https://go.dev/play/p/P3-9MdcXegR
 func FilterByValues[K comparable, V comparable](m map[K]V, values []V) map[K]V {
 	result := make(map[K]V)
 
@@ -124,7 +124,7 @@ func FilterByValues[K comparable, V comparable](m map[K]V, values []V) map[K]V {
 }
 
 // OmitBy is the opposite of Filter, removes all the map elements for which the predicate function returns true.
-// Play: todo
+// Play: https://go.dev/play/p/YJM4Hj5hNwm
 func OmitBy[K comparable, V any](m map[K]V, predicate func(key K, value V) bool) map[K]V {
 	result := make(map[K]V)
 
@@ -137,7 +137,7 @@ func OmitBy[K comparable, V any](m map[K]V, predicate func(key K, value V) bool)
 }
 
 // OmitByKeys the opposite of FilterByKeys, extracts all the map elements which keys are not omitted.
-// Play: todo
+// Play: https://go.dev/play/p/jXGrWDBfSRp
 func OmitByKeys[K comparable, V any](m map[K]V, keys []K) map[K]V {
 	result := make(map[K]V)
 
@@ -150,7 +150,7 @@ func OmitByKeys[K comparable, V any](m map[K]V, keys []K) map[K]V {
 }
 
 // OmitByValues the opposite of FilterByValues. remov all elements whose value are in the give slice.
-// Play: todo
+// Play: https://go.dev/play/p/XB7Y10uw20_U
 func OmitByValues[K comparable, V comparable](m map[K]V, values []V) map[K]V {
 	result := make(map[K]V)
 
@@ -227,7 +227,7 @@ type Entry[K comparable, V any] struct {
 }
 
 // Entries transforms a map into array of key/value pairs.
-// Play: todo
+// Play: https://go.dev/play/p/Ltb11LNcElY
 func Entries[K comparable, V any](m map[K]V) []Entry[K, V] {
 	entries := make([]Entry[K, V], 0, len(m))
 
@@ -242,7 +242,7 @@ func Entries[K comparable, V any](m map[K]V) []Entry[K, V] {
 }
 
 // FromEntries creates a map based on a slice of key/value pairs
-// Play: todo
+// Play: https://go.dev/play/p/fTdu4sCNjQO
 func FromEntries[K comparable, V any](entries []Entry[K, V]) map[K]V {
 	result := make(map[K]V, len(entries))
 
@@ -254,7 +254,7 @@ func FromEntries[K comparable, V any](entries []Entry[K, V]) map[K]V {
 }
 
 // Transform a map to another type map.
-// Play: todo
+// Play: https://go.dev/play/p/P6ovfToM3zj
 func Transform[K1 comparable, V1 any, K2 comparable, V2 any](m map[K1]V1, iteratee func(key K1, value V1) (K2, V2)) map[K2]V2 {
 	result := make(map[K2]V2, len(m))
 
@@ -267,7 +267,7 @@ func Transform[K1 comparable, V1 any, K2 comparable, V2 any](m map[K1]V1, iterat
 }
 
 // MapKeys transforms a map to other type map by manipulating it's keys.
-// Play: todo
+// Play: https://go.dev/play/p/8scDxWeBDKd
 func MapKeys[K comparable, V any, T comparable](m map[K]V, iteratee func(key K, value V) T) map[T]V {
 	result := make(map[T]V, len(m))
 
@@ -279,7 +279,7 @@ func MapKeys[K comparable, V any, T comparable](m map[K]V, iteratee func(key K,
 }
 
 // MapValues transforms a map to other type map by manipulating it's values.
-// Play: todo
+// Play: https://go.dev/play/p/g92aY3fc7Iw
 func MapValues[K comparable, V any, T any](m map[K]V, iteratee func(key K, value V) T) map[K]T {
 	result := make(map[K]T, len(m))