add executor and refactor graph traverse

.gitignore

@@ -441,6 +441,9 @@ data
 *.so
 *.pdf
 
+# Test cache
+tests/*.png
+
 # Exclude pdf in assets
 !assets/*.pdf
 

docs/sys_design/serve_layer/graph.md

@@ -7,7 +7,7 @@ Parrot's Graph is the core information we capture from the application, which de
 
 To help readers have a vertical understanding of our system, we first explain our data pipeline in the Serve Layer, starting from a request coming from the Parrot API.
 
-- Step 1: The request comes to the `semantic_call/` API route and the core call `submit_semantic_call`.
+- Step 1: The request comes to the `semantic_call/` API route and the core calls `submit_semantic_call`.
 - Step 2: The core finds the corresponding `Session` and calls its `add_request` method.
 - Step 3: The session parses the request payload to the class `ChunkedSemanticCallRequest`.
 - Step 4: Convert the `ChunkedSemanticCallRequest` into `RequestChain`, which consists of several `CompletionChain`.

docs/user_docs/parrot_apis.md

@@ -57,6 +57,7 @@ Request body:
 
 ```json
 {
+    "func_name": "xxx", // Function name. (Not very important)
     "template": "This is a test {{a}} function. {{b}}",
     "parameters": [
         {