diff --git a/README.md b/README.md
index 54e2369..f7307f1 100644
--- a/README.md
+++ b/README.md
@@ -30,7 +30,8 @@ Hence, I built this framework that lets LLMs focus on what matters. It turns out
   <img src="/assets/minillmflow.jpg" width="400"/>
 </div>
 
-## Example
+## Example LLM apps
 
-- Beginner Tutorial on [Text summarization + QA agent](https://colab.research.google.com/github/zachary62/miniLLMFlow/blob/main/cookbook/demo.ipynb)
-- Have questions for this tutorial? Try [this prompt](https://chatgpt.com/share/676f16d2-7064-8000-b9d7-f6874346a6b5)
+- Beginner Tutorial: [Text summarization for Paul Graham Essay + QA agent](https://colab.research.google.com/github/zachary62/miniLLMFlow/blob/main/cookbook/demo.ipynb)
+
+    - Have questions for this tutorial? Ask LLM assistants through [this prompt](https://chatgpt.com/share/676f16d2-7064-8000-b9d7-f6874346a6b5)
diff --git a/docs/async.md b/docs/async.md
index 9d8e98e..e366327 100644
--- a/docs/async.md
+++ b/docs/async.md
@@ -1,7 +1,7 @@
 ---
 layout: default
 title: "Async"
-nav_order: 6
+nav_order: 7
 ---
 
 # Async
@@ -15,7 +15,7 @@ nav_order: 6
 
 An **AsyncNode** is like a normal `Node`, except `exec()` (and optionally `prep()`) can be declared **async**. You can `await` inside these methods. For example:
 
-`` 
+```python
 class AsyncSummarizeFile(AsyncNode):
     async def prep(self, shared):
         # Possibly do async file reads or small concurrency tasks
@@ -37,7 +37,7 @@ class AsyncSummarizeFile(AsyncNode):
         filename = self.params["filename"]
         shared["summary"][filename] = exec_res
         return "default"
-``
+```
 
 - **`prep(shared)`** can be `async def` if you want to do asynchronous pre-processing.
 - **`exec(shared, prep_res)`** is typically the main place for async logic.
@@ -49,7 +49,7 @@ An **AsyncFlow** is a Flow where nodes can be **AsyncNode**s or normal `Node`s.
 
 ### Minimal Example
 
-`` 
+```python
 class MyAsyncFlow(AsyncFlow):
     pass  # Usually, you just instantiate AsyncFlow with a start node
 
@@ -70,7 +70,7 @@ async def main():
     await my_flow.run(shared)
 
 asyncio.run(main())
-``
+```
 
 - If the start node or any subsequent node is an `AsyncNode`, the Flow automatically calls its `prep()`, `exec()`, `post()` as async functions.
 - You can mix normal `Node`s and `AsyncNode`s in the same flow. **AsyncFlow** will handle the difference seamlessly.
@@ -79,7 +79,7 @@ asyncio.run(main())
 
 If you want to run a batch of flows **concurrently**, you can use `BatchAsyncFlow`. Like `BatchFlow`, it generates a list of parameter sets in `prep()`, but each iteration runs the sub-flow asynchronously.
 
-`` 
+```python
 class SummarizeAllFilesAsync(BatchAsyncFlow):
     async def prep(self, shared):
         # Return a list of param dicts (like in BatchFlow),
@@ -94,7 +94,7 @@ all_files_flow = SummarizeAllFilesAsync(start=async_summarize_flow)
 
 # Then in your async context:
 await all_files_flow.run(shared)
-``
+```
 
 Under the hood:
 1. `prep()` returns a list of param sets.  
@@ -105,7 +105,7 @@ Under the hood:
 
 Just like normal Nodes, an `AsyncNode` can have `max_retries` and a `process_after_fail(...)` method:
 
-`` 
+```python
 class RetryAsyncNode(AsyncNode):
     def __init__(self, max_retries=3):
         super().__init__(max_retries=max_retries)
@@ -118,7 +118,7 @@ class RetryAsyncNode(AsyncNode):
     def process_after_fail(self, shared, prep_res, exc):
         # Provide fallback response
         return "Unable to complete async call due to error."
-``
+```
 
 ## 5. Best Practices
 
diff --git a/docs/batch.md b/docs/batch.md
index 12b70a4..540de5a 100644
--- a/docs/batch.md
+++ b/docs/batch.md
@@ -1,7 +1,7 @@
 ---
 layout: default
 title: "Batch"
-nav_order: 5
+nav_order: 6
 ---
 
 # Batch
@@ -22,7 +22,7 @@ A **BatchNode** extends `Node` but changes how `prep()` and `exec()` behave:
 
 ### Example: Map Summaries
 
-`` 
+```python
 class MapSummaries(BatchNode):
     def prep(self, shared):
         # Suppose we have a big file; we want to chunk it
@@ -43,14 +43,14 @@ class MapSummaries(BatchNode):
         combined = "\n".join(exec_res_list)
         shared["summary"]["large_text.txt"] = combined
         return "default"
-``
+```
 
 **Flow** usage:
-`` 
+```python
 map_summaries = MapSummaries()
 flow = Flow(start=map_summaries)
 flow.run(shared)
-``
+```
 
 - After `prep()` returns multiple chunks, `exec()` is called for each chunk. 
 - The aggregated `exec_res_list` is passed to `post()`, where you can do final processing.
@@ -69,7 +69,7 @@ A **BatchFlow** runs a **Flow** multiple times, each time with a different set o
 
 ### Example: Summarize Many Files
 
-`` 
+```python
 class SummarizeAllFiles(BatchFlow):
     def prep(self, shared):
         # Return a list of parameter dicts (one per file)
@@ -78,11 +78,11 @@ class SummarizeAllFiles(BatchFlow):
         return params_list
 
     # No custom exec() or post(), so we rely on BatchFlow’s default
-``
+```
 
 Then define a **Flow** that handles **one** file. Suppose we have `Flow(start=summarize_file)`.  
 
-`` 
+```python
 # Example "per-file" flow (just one node):
 summarize_file = SummarizeFile()
 
@@ -94,7 +94,7 @@ summarize_all_files = SummarizeAllFiles(start=summarize_file)
 
 # Running it:
 summarize_all_files.run(shared)
-``
+```
 
 **Under the hood**:
 1. `prep(shared)` in `SummarizeAllFiles` returns a list of param dicts, e.g., `[{filename: "file1.txt"}, {filename: "file2.txt"}, ...]`.
@@ -125,7 +125,7 @@ This can be done by making the **outer** BatchFlow’s `exec()` return a list of
 
 ## 4. Putting It All Together
 
-`` 
+```python
 # We'll combine the ideas:
 class MapSummaries(BatchNode):
     def prep(self, shared):
@@ -157,7 +157,7 @@ class SummarizeAllFiles(BatchFlow):
 # For now, let's just show usage:
 summarize_all = SummarizeAllFiles(start=map_flow)
 summarize_all.run(shared)
-``
+```
 
 In this snippet:
 
diff --git a/docs/communication.md b/docs/communication.md
index cefe077..b4115f6 100644
--- a/docs/communication.md
+++ b/docs/communication.md
@@ -1,7 +1,7 @@
 ---
 layout: default
 title: "Communication"
-nav_order: 4
+nav_order: 5
 ---
 
 # Communication
@@ -20,9 +20,9 @@ This design avoids complex message-passing or data routing. It also lets you **n
 ### Overview
 
 A shared store is typically a Python dictionary, like:
-`` 
+```python
 shared = {"data": {}, "summary": {}, "config": { ... }, ...}
-``
+```
 
 Every Node’s `prep()`, `exec()`, and `post()` methods receive the **same** `shared` object. This makes it easy to:
 - Read data that another Node loaded, such as a text file or database record.
@@ -31,7 +31,7 @@ Every Node’s `prep()`, `exec()`, and `post()` methods receive the **same** `sh
 
 ### Example
 
-`` 
+```python
 class LoadData(Node):
     def prep(self, shared):
         # Suppose we read from disk or an API
@@ -59,7 +59,7 @@ class Summarize(Node):
     def post(self, shared, prep_res, exec_res):
         shared["summary"]["my_file.txt"] = exec_res
         return "default"
-``
+```
 
 Here,
 - `LoadData` writes to `shared["data"]`.
@@ -86,7 +86,7 @@ Common examples:
 
 ### Example
 
-`` 
+```python
 # 1) Create a Node that uses params
 class SummarizeFile(Node):
     def prep(self, shared):
@@ -109,7 +109,7 @@ node.set_params({"filename": "doc1.txt"})
 
 # 3) Run
 node.run(shared)
-``
+```
 
 Because **params** are only for that Node, you don’t pollute the global `shared` with fields that might only matter to one operation.
 
@@ -147,7 +147,7 @@ Because **params** are only for that Node, you don’t pollute the global `share
 
 ## Putting It All Together
 
-`` 
+```python
 # Suppose you have a flow:
 load_data >> summarize_file
 my_flow = Flow(start=load_data)
@@ -164,7 +164,7 @@ shared = {
 
 my_flow.run(shared)
 # After run, shared["summary"]["my_text.txt"] might have the LLM summary
-``
+```
 
 - `load_data` uses its param (`"path"`) to load some data into `shared["data"]`.
 - `summarize_file` uses its param (`"filename"`) to pick which file from `shared["data"]` to summarize.
diff --git a/docs/flow.md b/docs/flow.md
index 328bbcf..a4008c4 100644
--- a/docs/flow.md
+++ b/docs/flow.md
@@ -1,74 +1,33 @@
 ---
 layout: default
 title: "Flow"
-nav_order: 2
+nav_order: 4
 ---
 
 # Flow
 
-In **Mini LLM Flow**, a **Flow** orchestrates how Nodes connect and run, based on **Actions** returned from each Node’s `post()` method. You can chain Nodes in a sequence or create branching logic depending on the **Action** string.
+A **Flow** orchestrates how Nodes connect and run, based on **Actions** returned from each Node’s `post()` method. You can chain Nodes in a sequence or create branching logic depending on the **Action** string.
 
 ## Action-based Transitions
 
-Each Node’s `post(shared, prep_res, exec_res)` returns a string called **Action**. By default, if `post()` doesn’t explicitly return anything, we treat that as `"default"`.
+Each Node's `post(shared, prep_res, exec_res)` method returns an **Action** string. By default, if `post()` doesn't explicitly return anything, we treat that as `"default"`.
 
 You define transitions with the syntax:
 
-```python 
-node_a >> node_b
-```  
-- This means if `node_a.post()` returns `"default"` (or `None`), go to `node_b`.
+1. Basic default transition: `node_a >> node_b`
+  This means if `node_a.post()` returns `"default"` (or `None`), go to `node_b`. 
+  (Equivalent to `node_a - "default" >> node_b`)
 
-```python
-node_a - "action_name" >> node_b
-```  
-- This means if `node_a.post()` returns `"action_name"`, go to `node_b`.
+2. Named action transition: `node_a - "action_name" >> node_b`
+  This means if `node_a.post()` returns `"action_name"`, go to `node_b`.
 
-It’s possible to create loops, branching, or multi-step flows. You can also chain with multiple Actions from a single node to different successors:
-
-```python
-# Define nodes for order processing
-validate_order = ValidateOrderNode()
-check_inventory = CheckInventoryNode()
-process_payment = ProcessPaymentNode()
-send_confirmation = SendConfirmationNode()
-notify_backorder = NotifyBackorderNode()
-
-# Define the flow
-validate_order - "valid" >> check_inventory
-validate_order - "invalid" >> send_confirmation  # Send rejection confirmation
-
-check_inventory - "in_stock" >> process_payment
-check_inventory - "out_of_stock" >> notify_backorder
-
-process_payment - "success" >> send_confirmation
-process_payment - "failure" >> send_confirmation  # Send payment failure notice
-```
-
-```mermaid
-flowchart TD
-    validate[Validate Order] -->|valid| inventory[Check Inventory]
-    validate -->|invalid| confirm[Send Confirmation]
-    
-    inventory -->|in_stock| payment[Process Payment]
-    inventory -->|out_of_stock| backorder[Notify Backorder]
-    
-    payment -->|success| confirm
-    payment -->|failure| confirm
-
-    style validate fill:#d4f1f9
-    style confirm fill:#d4f1f9
-```
+It’s possible to create loops, branching, or multi-step flows. You can also chain with multiple Actions from a single node to different successors.
 
 ## Creating a Flow
 
 A **Flow** begins with a **start** node (or flow). You call `Flow(start=some_node)` to specify the entry point. When you call `flow.run(shared)`, it executes the first node, looks at its `post()` return Action, follows the corresponding transition, and continues until there’s no next node or you explicitly stop.
 
-```flow = Flow(start=node_a)```
-
-
-
-## Example: Simple Sequence
+### Example: Simple Sequence
 
 Here’s a minimal flow of two nodes in a chain:
 
@@ -83,69 +42,123 @@ flow.run(shared)
 - The flow then sees `"default"` Action is linked to `node_b` and runs `node_b`.  
 - If `node_b.post()` returns `"default"` but we didn’t define `node_b >> something_else`, the flow ends there.
 
-## Example: Branching & Looping
+### Example: Branching & Looping
 
-Suppose `FindRelevantFile` can return three possible Actions in its `post()`:
+Here's a simple expense approval flow that demonstrates branching and looping. The `ReviewExpense` node can return three possible Actions:
 
-- `"end"`: means no question, so stop.  
-- `"answer"`: means we have a relevant file, move to `AnswerQuestion`.  
-- `"retry"`: means no relevant file found, try again.
+- `"approved"`: expense is approved, move to payment processing
+- `"needs_revision"`: expense needs changes, send back for revision 
+- `"rejected"`: expense is denied, end the process
 
-We can wire them:
+We can wire them like this:
 
-``` 
-find_relevant_file - "end"    >> no_op_node
-find_relevant_file - "answer" >> answer_question
-find_relevant_file - "retry"  >> find_relevant_file
-flow = Flow(start=find_relevant_file)
+```python
+# Define the flow connections
+review - "approved" >> payment        # If approved, process payment
+review - "needs_revision" >> revise   # If needs changes, go to revision
+review - "rejected" >> end           # If rejected, end the process
+
+revise >> review   # After revision, go back for another review
+payment >> end     # After payment, end the process
+
+flow = Flow(start=review)
 ```
 
-1. If `FindRelevantFile.post()` returns `"answer"`, the flow calls `answer_question`.
-2. If `FindRelevantFile.post()` returns `"retry"`, it loops back to itself.
-3. If `"end"`, it goes to `no_op_node`. If `no_op_node` has no further transitions, the flow stops.
+Let's see how it flows:
+
+1. If `review.post()` returns `"approved"`, the expense moves to `payment` node
+2. If `review.post()` returns `"needs_revision"`, it goes to `revise` node, which then loops back to `review`
+3. If `review.post()` returns `"rejected"`, it moves to `end` node and stops
+
+```mermaid
+flowchart TD
+    review[Review Expense] -->|approved| payment[Process Payment]
+    review -->|needs_revision| revise[Revise Report]
+    review -->|rejected| end[End Process]
+    
+    revise --> review
+    payment --> end
+```
 
 ## Running Individual Nodes vs. Running a Flow
 
-- **`node.run(shared)`**: Just runs that node alone (calls `prep()`, `exec()`, `post()`), returns an Action. **Does not** proceed automatically to the successor. This is mainly for debugging or testing a single node.
+- **`node.run(shared)`**: Just runs that node alone (calls `prep()`, `exec()`, `post()`), returns an Action. ⚠️ **Does not** proceed automatically to the successor and may use incorrect parameters. This is mainly for debugging or testing a single node.
 - **`flow.run(shared)`**: Executes from the start node, follows Actions to the next node, and so on until the flow can’t continue (no next node or no next Action).
 
 Always use `flow.run(...)` in production to ensure the full pipeline runs correctly.
 
 ## Nested Flows
 
-A **Flow** can act like a Node. That means you can do:
+A **Flow** can act like a Node, which enables powerful composition patterns. This means you can:
 
-```some_flow >> another_node```  
-or treat `some_flow` as a node inside a larger flow. This helps you compose complex pipelines by nesting smaller flows.
+1. Use a flow as a node within another flow's transitions
+2. Combine multiple smaller flows into a larger pipeline
+3. Create reusable flow components
 
-## Example Code
+### Basic Flow Nesting
 
-Below is a short snippet combining these ideas:
+Here's how to connect a flow to another node:
 
-``` 
-# Define nodes
-find_file = FindRelevantFile()
-answer    = AnswerQuestion()
-no_op     = NoOp()
+```python
+# Create a sub-flow
+node_a >> node_b
+subflow = Flow(start=node_a)
 
-# Define transitions
-find_file - "answer" >> answer
-find_file - "retry"  >> find_file
-find_file - "end"    >> no_op
+# Connect it to another node
+subflow >> node_c
 
-# Build the Flow
-qa_flow = Flow(start=find_file)
-
-# Run
-qa_flow.run(shared)
+# Create the parent flow
+parent_flow = Flow(start=subflow)
 ```
 
-When `find_file`’s `post()` returns `"answer"`, we proceed to `answer`. If it returns `"retry"`, we loop back. If `"end"`, we move on to `no_op`.
+When `parent_flow.run()` executes:
+1. It starts `subflow`
+2. `subflow` runs through its nodes (`node_a` then `node_b`)
+3. After `subflow` completes, execution continues to `node_c`
 
----
+### Example: Order Processing Pipeline
 
-**That’s Flow in a nutshell:**  
-- **Actions** determine which node runs next.  
-- **Flow** runs the pipeline from the start node to completion.  
-- You can chain nodes in a linear sequence or build loops and branches.  
-- Nodes can themselves be entire flows, allowing nested graph structures.
\ No newline at end of file
+Here's a practical example that breaks down order processing into nested flows:
+
+```python
+# Payment processing sub-flow
+validate_payment >> process_payment >> payment_confirmation
+payment_flow = Flow(start=validate_payment)
+
+# Inventory sub-flow
+check_stock >> reserve_items >> update_inventory
+inventory_flow = Flow(start=check_stock)
+
+# Shipping sub-flow
+create_label >> assign_carrier >> schedule_pickup
+shipping_flow = Flow(start=create_label)
+
+# Connect the flows into a main order pipeline
+payment_flow >> inventory_flow >> shipping_flow
+
+# Create the master flow
+order_pipeline = Flow(start=payment_flow)
+
+# Run the entire pipeline
+order_pipeline.run(shared_data)
+```
+
+This creates a clean separation of concerns while maintaining a clear execution path:
+
+```mermaid
+flowchart TD
+   subgraph "Payment Flow"
+   A[Validate Payment] --> B[Process Payment] --> C[Payment Confirmation]
+   end
+   
+   subgraph "Inventory Flow"
+   D[Check Stock] --> E[Reserve Items] --> F[Update Inventory]
+   end
+   
+   subgraph "Shipping Flow"
+   G[Create Label] --> H[Assign Carrier] --> I[Schedule Pickup]
+   end
+   
+   Payment Flow --> Inventory Flow
+   Inventory Flow --> Shipping Flow
+```
diff --git a/docs/index.md b/docs/index.md
index 9cd7db0..b2f94ee 100644
--- a/docs/index.md
+++ b/docs/index.md
@@ -10,16 +10,20 @@ A [100-line](https://github.com/zachary62/miniLLMFlow/blob/main/minillmflow/__in
 
 We model the LLM workflow as a **Nested Flow**:
 - Each **Node** handles a simple LLM task.
-- Nodes are chained together to form a **Flow** for more complex tasks.
-- One Node can be chained to multiple Nodes based on **Actions**.
+- Nodes are chained together to form a **Flow** for compute-intensive tasks.
+- One Node can be chained to multiple Nodes through **Actions** as an agent.
 - A Flow can be treated as a Node for **Nested Flows**.
 - Both Nodes and Flows can be **Batched** for data-intensive tasks.
-- Nodes and Flows can be **Async**.
+- Nodes and Flows can be **Async** for user inputs.
 
 <div align="center">
   <img src="https://github.com/zachary62/miniLLMFlow/blob/main/assets/minillmflow.jpg?raw=true" width="400"/>
 </div>
 
+## Preparation
+
+- [LLM Integration](./llm.md)
+
 ## Core Abstraction
 
 - [Node](./node.md)
diff --git a/docs/llm.md b/docs/llm.md
new file mode 100644
index 0000000..fd49f9a
--- /dev/null
+++ b/docs/llm.md
@@ -0,0 +1,74 @@
+---
+layout: default
+title: "LLM Integration"
+nav_order: 3
+---
+
+# Call LLM 
+
+For your LLM application, implement a function to call LLMs yourself. 
+You can ask an assistant like ChatGPT or Claude to generate an example. 
+For instance, asking ChatGPT to "implement a `call_llm` function that takes a prompt and returns the LLM response" gives:
+
+```python
+def call_llm(prompt):
+    from openai import OpenAI
+    # Set the OpenAI API key (use environment variables, etc.)
+    client = OpenAI(api_key="YOUR_API_KEY_HERE")
+    r = client.chat.completions.create(
+        model="gpt-4",
+        messages=[{"role": "user", "content": prompt}]
+    )
+    return r.choices[0].message.content
+
+# Example usage
+call_llm("How are you?")
+```
+
+## Improvements
+You can enhance the function as needed. Examples:
+
+1. Handle chat history:
+
+```python
+def call_llm(messages):
+    from openai import OpenAI
+    client = OpenAI(api_key="YOUR_API_KEY_HERE")
+    r = client.chat.completions.create(
+        model="gpt-4",
+        messages=messages
+    )
+    return r.choices[0].message.content
+```
+
+2. Add in-memory caching:
+
+```python
+from functools import lru_cache
+
+@lru_cache(maxsize=1000)
+def call_llm(prompt):
+    # Your implementation here
+    pass
+```
+
+3. Enable logging:
+
+```python
+def call_llm(prompt):
+    import logging
+    logging.info(f"Prompt: {prompt}")
+    response = ...
+    logging.info(f"Response: {response}")
+    return response
+```
+
+You can also try libraries like `litellm`
+
+## Why not provide an LLM call function?
+I believe it is a bad practice to provide LLM-specific implementations in a general framework:
+- LLM APIs change frequently. Hardcoding them makes maintenance difficult.
+- You may need flexibility to switch vendors, use fine-tuned models, or deploy local LLMs.
+- Custom optimizations like prompt caching, request batching, or response streaming may be required.
+
+
diff --git a/docs/node.md b/docs/node.md
index 30d9e1b..22bc81b 100644
--- a/docs/node.md
+++ b/docs/node.md
@@ -1,7 +1,7 @@
 ---
 layout: default
 title: "Node"
-nav_order: 2
+nav_order: 3
 ---
 
 # Node