How to create a double conditional flow?

[javixeneize]

Hi

I want to create a graph as per the image attached. The logic should be:

The assistant will receive a question, depending on the question, it might call the tool

Then, it will call the verifier to double check the result. The verifier (another llm) will decide if the answer is accurate, which will lead to the end of the graph, or notify back the assistant that the answer is not correct, and will go to the previous point

any idea how can i implement this using langgraph? My graph without the verifier works:

    builder.add_node("assistant", assistant)
    builder.add_node("tools", ToolNode(tools))
    builder.add_edge(START, "assistant")
    builder.add_conditional_edges(
        "assistant",
        tools_condition,
    )
    builder.add_edge("tools", "assistant")

But when i add the verifier logic, it fails.

 builder.add_node("verifier", verifier)
    builder.add_conditional_edges(
        "assistant",
        "verifier",
    )
    builder.add_conditional_edges(
        "verifier",
        "assistant",
    )

any idea how can i implement this using langgraph?

Thanks