Human-in-the-loop with LangGraph in LangChain - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to import the HumanLoop class from langgraph.

LangChain

from langgraph import [1]

Drag options to blanks, or click blank then click option'

APrompt

BAgent

CHumanLoop

DChain

Attempts:

3 left

💡 Hint

Common Mistakes

Importing unrelated classes like Agent or Chain.

Misspelling the class name.

The HumanLoop class is imported from langgraph to create human-in-the-loop workflows.

2fill in blank

medium

Complete the code to create a HumanLoop instance with the name 'review_loop'.

LangChain

loop = HumanLoop(name=[1])

Drag options to blanks, or click blank then click option'

A'review_loop'

B'check_loop'

C'loop_review'

D'human_review'

Attempts:

3 left

💡 Hint

Common Mistakes

Using a different name than 'review_loop'.

Forgetting quotes around the string.

The HumanLoop instance is named 'review_loop' to identify the human review step.

3fill in blank

hard

Fix the error in the code to add a human review step to the LangGraph chain.

LangChain

chain.add_step([1])

Drag options to blanks, or click blank then click option'

AHumanLoop

BHumanLoop('review_loop')

CHumanLoop()

DHumanLoop(name='review_loop')

Attempts:

3 left

💡 Hint

Common Mistakes

Passing the class itself instead of an instance.

Omitting the name parameter.

The add_step method requires an instance of HumanLoop with the name parameter specified.

4fill in blank

hard

Fill both blanks to define a LangGraph chain with a human-in-the-loop review step and run it with input 'data'.

LangChain

chain = LangGraph().add_step([1])
result = chain.[2](input_data='data')

Drag options to blanks, or click blank then click option'

AHumanLoop(name='review_loop')

Brun

Cexecute

Dstart

Attempts:

3 left

💡 Hint

Common Mistakes

Using the wrong method name to run the chain.

Not creating the HumanLoop instance properly.

The chain adds a HumanLoop step named 'review_loop' and runs with the run method.

5fill in blank

hard

Fill all three blanks to create a LangGraph chain with a human loop, set a prompt, and run it with user input.

LangChain

loop = HumanLoop(name=[1])
chain = LangGraph().add_step(loop).set_prompt([2])
output = chain.[3](input_data='user input')

Drag options to blanks, or click blank then click option'

A'human_review'

B'Please review the output:'

Crun

Dexecute

Attempts:

3 left

💡 Hint

Common Mistakes

Using incorrect names or prompt strings.

Using the wrong method to run the chain.

The human loop is named 'human_review', the prompt is set to 'Please review the output:', and the chain is run with the run method.

Practice

1. What is the main purpose of using Human-in-the-loop with LangGraph?

easy

A. To combine AI processing steps with human feedback for better results

B. To replace human input entirely with AI automation

C. To create static AI models without any human interaction

D. To speed up AI training by skipping validation steps

Solution

1. Step 1: Understand Human-in-the-loop concept

   Human-in-the-loop means AI and humans work together, where humans check or improve AI outputs.

2. Step 2: Role of LangGraph in this context

   LangGraph helps build flows that connect AI steps with human feedback nodes to improve results.

3. Final Answer:

   To combine AI processing steps with human feedback for better results -> Option A

4. Quick Check:

   Human-in-the-loop = AI + human feedback [OK]

Hint: Human-in-the-loop means AI plus human checks [OK]

Common Mistakes:

• Thinking it removes human input
• Assuming it only automates AI without feedback
• Confusing it with fully automated AI pipelines

2. Which of the following is the correct way to add a human feedback node in a LangGraph flow?

easy

A. flow.create_human('review')

B. flow.add_human('review')

C. flow.add_node(HumanNode(name='review'))

D. flow.insert_human_node('review')

Solution

1. Step 1: Recall LangGraph syntax for adding nodes

   LangGraph uses flow.add_node() method to add nodes, including human nodes.

2. Step 2: Identify correct human node creation

   HumanNode is the class representing human feedback nodes, so flow.add_node(HumanNode(name='review')) is correct.

3. Final Answer:

   flow.add_node(HumanNode(name='review')) -> Option C

4. Quick Check:

   Use add_node with HumanNode class [OK]

Hint: Use add_node with HumanNode to add human steps [OK]

Common Mistakes:

• Using non-existent methods like add_human or insert_human_node
• Forgetting to instantiate HumanNode class
• Passing string directly without node wrapper

3. Given this LangGraph flow snippet:

flow.add_node(AINode(name='generate'))
flow.add_node(HumanNode(name='check'))
flow.connect('generate', 'check')
result = flow.run(input='Hello')

What will happen when flow.run is called?

medium

A. The flow runs human node first, then AI node

B. The flow runs only the AI node and skips the human node

C. The flow throws an error because human nodes cannot be connected

D. The AI node generates output, then the human node requests feedback before continuing

Solution

1. Step 1: Analyze flow node order and connections

   The AI node 'generate' runs first, then its output is passed to the human node 'check' via connect.

2. Step 2: Understand human node behavior in flow.run

   HumanNode pauses for human feedback before continuing, so the flow waits for human input after AI output.

3. Final Answer:

   The AI node generates output, then the human node requests feedback before continuing -> Option D

4. Quick Check:

   AI runs first, then human feedback [OK]

Hint: AI node runs before connected human node in flow [OK]

Common Mistakes:

• Assuming human nodes are skipped automatically
• Thinking human nodes run before AI nodes
• Believing human nodes cause errors when connected

4. You wrote this code snippet:

flow.add_node(HumanNode('review'))
flow.connect('review', 'generate')

But it throws an error. What is the likely cause?

medium

A. HumanNode must be instantiated with a named argument like name='review'

B. You cannot connect a human node to an AI node

C. The connect method requires node objects, not strings

D. HumanNode cannot be added to LangGraph flows

Solution

1. Step 1: Check HumanNode instantiation syntax

   HumanNode requires named argument 'name', so HumanNode('review') is invalid syntax.

2. Step 2: Confirm connection method accepts node names as strings

   Connecting nodes by their names as strings is valid, so error is not from connect method usage.

3. Final Answer:

   HumanNode must be instantiated with a named argument like name='review' -> Option A

4. Quick Check:

   HumanNode needs name= argument [OK]

Hint: HumanNode requires name= parameter when created [OK]

Common Mistakes:

• Passing positional argument instead of named argument
• Assuming connect only accepts node objects
• Thinking human nodes cannot be connected

5. You want to build a LangGraph flow where AI generates text, a human reviews and edits it, then AI summarizes the final text. Which flow setup correctly implements this?

hard

A. flow.add_node(AINode(name='generate'))
flow.add_node(AINode(name='summarize'))
flow.add_node(HumanNode(name='review'))
flow.connect('generate', 'summarize')
flow.connect('summarize', 'review')

B. flow.add_node(AINode(name='generate'))
flow.add_node(HumanNode(name='review'))
flow.add_node(AINode(name='summarize'))
flow.connect('generate', 'review')
flow.connect('review', 'summarize')

C. flow.add_node(HumanNode(name='review'))
flow.add_node(AINode(name='generate'))
flow.add_node(AINode(name='summarize'))
flow.connect('review', 'generate')
flow.connect('generate', 'summarize')

D. flow.add_node(AINode(name='generate'))
flow.add_node(HumanNode(name='review'))
flow.add_node(AINode(name='summarize'))
flow.connect('review', 'generate')
flow.connect('summarize', 'review')

Solution

1. Step 1: Identify correct node order for the flow

   The flow should be AI generate -> human review/edit -> AI summarize final text.

2. Step 2: Check connections match the desired order

   flow.add_node(AINode(name='generate')) flow.add_node(HumanNode(name='review')) flow.add_node(AINode(name='summarize')) flow.connect('generate', 'review') flow.connect('review', 'summarize') connects 'generate' to 'review', then 'review' to 'summarize', matching the required sequence.

3. Final Answer:

   AI generate, then human review, then AI summarize with correct connections -> Option B

4. Quick Check:

   Correct node order and connections = flow.add_node(AINode(name='generate')) flow.add_node(HumanNode(name='review')) flow.add_node(AINode(name='summarize')) flow.connect('generate', 'review') flow.connect('review', 'summarize') [OK]

Hint: Connect nodes in logical order: AI -> Human -> AI [OK]

Common Mistakes:

• Placing human node before AI generate
• Connecting nodes in wrong sequence
• Skipping human review step