View difference between Paste ID: LdPKTSfG and DzFbVUXw

 -module(esyntax).
 -compile(export_all).
 
 f() ->
 	FunctionBuilder = function_builder(get_send_msg_info),
 	ClauseBuilder = clause_builder([], none),
-	FunctionBuilder(ClauseBuilder(erl_syntax:list(erl_syntax:atom(abz)))).
+	FunctionBuilder([ClauseBuilder([erl_syntax:atom(abz)])]).
 
 function_builder(FunctionName) ->
-	fun(Clauses) ->
+	fun(Clauses) when is_list(Clauses) ->
 			erl_syntax:function(erl_syntax:atom(FunctionName), Clauses)
 	end.
 
 clause_builder(Patterns, Guard) ->
-	fun(Body) ->
+	fun(Body) when is_list(Body) ->
 			erl_syntax:clause(Patterns, Guard, Body)
 	end.
 
 %%%%%%%%%%%%%
 
-55> SyntaxTree = esyntax:f().
+102> SyntaxTree = esyntax:f().
 {tree,function,
-    {attr,0,[],none},
+      {attr,0,[],none},
-    {function,
+      {function,{tree,atom,{attr,0,[],none},get_send_msg_info},
-        {tree,atom,{attr,0,[],none},get_send_msg_info},
+                [{tree,clause,
-        {tree,clause,
+                       {attr,0,[],none},
-            {attr,0,[],none},
+                       {clause,[],none,[{tree,atom,{attr,0,[],none},abz}]}}]}}
-            {clause,[],none,
+103> erl_syntax:revert(SyntaxTree).
-                {tree,list,
+{function,0,get_send_msg_info,0,
-                    {attr,0,[],none},
+          [{clause,0,[],[],[{atom,0,abz}]}]}