use obj.output which is the API to compose

Author: bobzhang

builtin/char_test.mbt

@@ -19,7 +19,7 @@ test "char subtraction" {
   inspect!(b - a, content="1")
 }
 
-
+///|
 test "char show" {
   assert_eq!('\b'.to_string(), "\u0008")
   // assert_eq!('\b'.to_string(), "\u{8}")
@@ -31,4 +31,3 @@ test "char show" {
   assert_eq!('\u0002'.to_string(), "\u0002")
   assert_eq!('\b'.to_string().escape(), "\"\\b\"")
 }
-

builtin/stringbuilder.mbt

@@ -17,7 +17,7 @@ pub fn StringBuilder::write_object[T : Show](
   self : StringBuilder,
   obj : T
 ) -> Unit {
-  self.write_string(obj.to_string())
+  obj.output(self)
 }
 
 ///|

immut/sorted_map/utils_test.mbt

@@ -80,11 +80,11 @@ test "iter" {
   inspect!(
     buf,
     content=
-      #|0: zero
-      #|1: one
-      #|2: two
-      #|3: three
-      #|8: eight
+      #|0: "zero"
+      #|1: "one"
+      #|2: "two"
+      #|3: "three"
+      #|8: "eight"
       #|(0, "zero")
       #|(1, "one")
       #|(2, "two")