diff --git a/README.md b/README.md
index 9425c52..0d7272d 100644
--- a/README.md
+++ b/README.md
@@ -485,15 +485,15 @@ running time:
 
 Nasal has 6 value types.Number,string,vector,hash,function,nil.
 
-Number has 3 formats.Dec,hex and oct;
+__Number__ has 3 formats.Dec,hex and oct;
 
-String has 3 formats.But the third one is often used to declare a character.
+__String__ has 3 formats.But the third one is often used to declare a character.
 
-Vector has unlimited length and can store all types of values.
+__Vector__ has unlimited length and can store all types of values.
 
-Hash is a hashmap that stores values with strings/identifiers as the key.
+__Hash__ is a hashmap that stores values with strings/identifiers as the key.
 
-Function is also a value type in nasal.
+__Function__ is also a value type in nasal.
 
 ```javascript
 var spc=nil;
@@ -591,25 +591,19 @@ var (a,b,c)=(0,1,2);
 ```javascript
 (a,b[0],c.d)=[0,1,2];
 (a,b[1],c.e)=(0,1,2);
+(a,b)=(b,a);
 ```
 
 ### conditional expression
 
 ```javascript
-if(1)
-{
+if(1){
     ;
-}
-elsif(2)
-{
+}elsif(2){
     ;
-}
-else if(3)
-{
+}else if(3){
     ;
-}
-else
-{
+}else{
     ;
 }
 ```
@@ -849,3 +843,6 @@ You will get an error of 'undefined symbol', instead of nothing happening in mos
 
 This change is __controversial__ among FGPRC's members.
 So maybe in the future i will use dynamic analysis again to cater to the habits of senior programmers.
+
+In this new interpreter, function doesn't put dynamic arguments into vector 'arg' automatically.
+So if you use 'arg' without definition, you'll get an error of 'undefined symbol'.
diff --git a/main.cpp b/main.cpp
index 0e751a2..ff61bef 100644
--- a/main.cpp
+++ b/main.cpp
@@ -67,8 +67,7 @@ void execute(std::string& file,std::string& command)
 		die("lexer",file);
 		return;
 	}
-	parse.set_toklist(lexer.get_token_list());
-	parse.main_process();
+	parse.main_process(lexer.get_token_list());
 	if(parse.get_error())
 	{
 		die("parse",file);
diff --git a/nasal_lexer.h b/nasal_lexer.h
index 5b330db..e97ee8c 100644
--- a/nasal_lexer.h
+++ b/nasal_lexer.h
@@ -90,7 +90,7 @@ struct token
     int line;
     int type;
     std::string str;
-	token(int l=0,int t=tok_null,std::string s=""){line=l;type=t;str=s;return;}
+	token(int l=0,int t=tok_null,std::string s=""){line=l;type=t;str=s;}
 };
 
 class nasal_lexer
diff --git a/nasal_parse.h b/nasal_parse.h
index 7def769..07e60ca 100644
--- a/nasal_parse.h
+++ b/nasal_parse.h
@@ -99,12 +99,12 @@ private:
     nasal_ast ret_expr();
 public:
     int get_error(){return error;}
-    void set_toklist(std::vector<token>& toks){tok_list=toks;}
-    void main_process();
+    void main_process(std::vector<token>&);
     nasal_ast& get_root(){return root;}
 };
-void nasal_parse::main_process()
+void nasal_parse::main_process(std::vector<token>& toks)
 {
+    tok_list=toks;
     ptr=in_function=in_loop=error=0;
     root.clear();
     error_token.clear();
diff --git a/test/ycombinator.nas b/test/ycombinator.nas
new file mode 100644
index 0000000..e1ab01f
--- /dev/null
+++ b/test/ycombinator.nas
@@ -0,0 +1,18 @@
+# Y combinator by ValKmjolnir
+
+import("lib.nas");
+var count=0;
+var fib=func(f){
+    return f(f);
+}(
+    func(f){
+        return func(x){
+            count+=1;
+            if(x<2) return x;
+            return f(f)(x-1)+f(f)(x-2);
+        }
+    }
+);
+
+for(var i=1;i<=20;i+=1)
+    println(fib(i));
\ No newline at end of file