doc: update doc for new added functions

convertor/convertor_test.go

@@ -466,12 +466,6 @@ func TestGbkToUtf8(t *testing.T) {
 	assert.Equal("hello", string(utf8Data))
 }
 
-func decodeBase64(data []byte) ([]byte, error) {
-	buf := make([]byte, base64.StdEncoding.DecodedLen(len(data)))
-	n, err := base64.StdEncoding.Decode(buf, data)
-	return buf[:n], err
-}
-
 func TestToStdBase64(t *testing.T) {
 	t.Parallel()
 	assert := internal.NewAssert(t, "TestToStdBase64")

strutil/string.go

@@ -599,6 +599,7 @@ func SubInBetween(str string, start string, end string) string {
 // HammingDistance calculates the Hamming distance between two strings.
 // The Hamming distance is the number of positions at which the corresponding symbols are different.
 // This func returns an error if the input strings are of unequal lengths.
+// Play: todo
 func HammingDistance(a, b string) (int, error) {
 	if len(a) != len(b) {
 		return -1, errors.New("a length and b length are unequal")