test: 增加例子代码

playground/Demo4/Main.snow

@@ -5,6 +5,7 @@ module: Main
         body:
            declare b1: boolean =true
            
+
         return b1
         end body
     end function

playground/Demo5/Main.snow

@@ -0,0 +1,21 @@
+module: Main
+    function: main
+        parameter:
+        return_type: int
+        body:
+            declare b1: boolean = false
+            loop:
+                initializer:
+                    declare i:int = 0
+                condition:
+                    b1
+                update:
+                    i = i + 1
+                body:
+
+                end body
+            end loop
+            return 0
+        end body
+    end function
+end module