Refactor encoding to use *string instead of string as input

I don't want to clone the whole input string

encoding/ascii_test.go

@@ -11,7 +11,7 @@ func TestASCIIEncodeSimpleASCIIString(t *testing.T) {
 	input := "Hello, World!"
 
 	expected := []byte{72, 101, 108, 108, 111, 44, 32, 87, 111, 114, 108, 100, 33}
-	err := coder.Encode(input, &buf)
+	err := coder.Encode(&input, &buf)
 
 	if err != nil {
 		t.Errorf("Expected no error, but got %v", err)
@@ -46,7 +46,7 @@ func TestASCIIEncodeEmptyString(t *testing.T) {
 	input := ""
 
 	expected := []byte{}
-	err := coder.Encode(input, &buf)
+	err := coder.Encode(&input, &buf)
 
 	if err != nil {
 		t.Errorf("Expected no error, but got %v", err)