Essay Writer. I haven't been able to make it work as it's shown in the video

Short Course Q&A AI Agents in LangGraph
1

First, It would die in the node research_plan_node, particular in this:
content = state['content'] or []

      2 queries = model.with_structured_output(Queries).invoke([
      3     SystemMessage(content=RESEARCH_PLAN_PROMPT),
      4     HumanMessage(content=state['task'])
      5 ])  
      6 print(state)
----> 7 content = content = state['content'] or []
      8 for q in queries.queries:
      9     response = tavily.search(query=q, max_results=2)

KeyError: 'content'

so I changed to content = state['content'] if 'content' in state else [] (also in the function research_critique_node)

That fixed the issue. However, I got another error:

ProgrammingError: SQLite objects created in a thread can only be used in that same thread. The object was created in thread id 8572948288 and this is thread id 6215086080.

Instead of using memory = SqliteSaver.from_conn_string(":memory:")because it was failing, I used sqlite3.connect as:

import sqlite3
conn = sqlite3.connect('checkpointer.db')
memory = SqliteSaver(conn)

graph = builder.compile(checkpointer=memory) 
.... <loop code here>

conn.close()

Later, I changed to use a block, as a content manager:

    graph = builder.compile(checkpointer=checkpointer)
    thread = {"configurable": {"thread_id": "1"}}
    for s in graph.stream({
        'task': "what is the difference between langchain and langsmith",
        "max_revisions": 2,
        "revision_number": 1,
    }, thread):
        print(s)

and that was fine. However, I cannot get the Essay Writer Interface to work.

Where can I find the helper library. Which one it’s using?

Thanks in advance!