> ## Documentation Index
> Fetch the complete documentation index at: https://phidatainc.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# Router with CEL: route based on a named previous step's output

> Uses previous_step_outputs map to access the classifier step by name, then routes to the appropriate handler based on the classification.

```python cel_previous_step_route.py theme={null}
"""Router with CEL: route based on a named previous step's output.
===============================================================

Uses previous_step_outputs map to access the classifier step by name,
then routes to the appropriate handler based on the classification.

Requirements:
    pip install cel-python
"""

from agno.agent import Agent
from agno.models.openai import OpenAIChat
from agno.workflow import CEL_AVAILABLE, Step, Workflow
from agno.workflow.router import Router

# ---------------------------------------------------------------------------
# Setup
# ---------------------------------------------------------------------------
if not CEL_AVAILABLE:
    print("CEL is not available. Install with: pip install cel-python")
    exit(1)

# ---------------------------------------------------------------------------
# Create Agents
# ---------------------------------------------------------------------------
classifier = Agent(
    name="Classifier",
    model=OpenAIChat(id="gpt-4o-mini"),
    instructions=(
        "Classify the request into exactly one category. "
        "Respond with only one word: BILLING, TECHNICAL, or GENERAL."
    ),
    markdown=False,
)

billing_agent = Agent(
    name="Billing Support",
    model=OpenAIChat(id="gpt-4o-mini"),
    instructions="You handle billing inquiries. Help with invoices, payments, and subscriptions.",
    markdown=True,
)

technical_agent = Agent(
    name="Technical Support",
    model=OpenAIChat(id="gpt-4o-mini"),
    instructions="You handle technical issues. Help with debugging and configuration.",
    markdown=True,
)

general_agent = Agent(
    name="General Support",
    model=OpenAIChat(id="gpt-4o-mini"),
    instructions="You handle general inquiries.",
    markdown=True,
)

# ---------------------------------------------------------------------------
# Create Workflow
# ---------------------------------------------------------------------------
workflow = Workflow(
    name="CEL Previous Step Outputs Router",
    steps=[
        Step(name="Classify", agent=classifier),
        Router(
            name="Support Router",
            # Access the classifier output by step name via previous_step_outputs map
            selector=(
                'previous_step_outputs.Classify.contains("BILLING") ? "Billing Support" : '
                'previous_step_outputs.Classify.contains("TECHNICAL") ? "Technical Support" : '
                '"General Support"'
            ),
            choices=[
                Step(name="Billing Support", agent=billing_agent),
                Step(name="Technical Support", agent=technical_agent),
                Step(name="General Support", agent=general_agent),
            ],
        ),
    ],
)

# ---------------------------------------------------------------------------
# Run Workflow
# ---------------------------------------------------------------------------
if __name__ == "__main__":
    print("--- Billing question ---")
    workflow.print_response(input="I was charged twice on my last invoice.")
    print()

    print("--- Technical question ---")
    workflow.print_response(input="My API keeps returning 503 errors.")
```

## Run the Example

<Steps>
  <Snippet file="create-venv-step.mdx" />

  <Step title="Install dependencies">
    ```bash theme={null}
    uv pip install -U agno cel-python fastapi openai
    ```
  </Step>

  <Step title="Export your OpenAI API key">
    <CodeGroup>
      ```bash Mac/Linux theme={null}
      export OPENAI_API_KEY="your_openai_api_key_here"
      ```

      ```bash Windows theme={null}
      $Env:OPENAI_API_KEY="your_openai_api_key_here"
      ```
    </CodeGroup>
  </Step>

  <Step title="Run the example">
    Save the code above as `cel_previous_step_route.py`, then run:

    ```bash theme={null}
    python cel_previous_step_route.py
    ```
  </Step>
</Steps>

Full source: [cookbook/04\_workflows/07\_cel\_expressions/router/cel\_previous\_step\_route.py](https://github.com/agno-agi/agno/blob/main/cookbook/04_workflows/07_cel_expressions/router/cel_previous_step_route.py)