Python values and functions

Learn in five minutes

• A function takes an input and returns an output.
• Strings, numbers, lists, and dicts cover the labs.
• A pure function is easier to test than a hidden global.
• Name the unit: tokens, milliseconds, or documents.
• Print the value and the unit together.

Agent code fails when a function both computes and secretly sends data. Split the calculation from the side effect so a test can call the calculation alone.

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Visual

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A toy token counter

1. Define a function that splits on spaces. Label it a toy, not a real tokenizer.
2. Assert that 'red fox' returns 2.
3. Pass an empty string and expect 0, not a crash.

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Quiz

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Ecosystem

Pure function

Same input, same output, no hidden write.

Sisters: Git, HTTP, JSON, unit tests.

A Python script can later call a local runner or a cloud API with the same JSON shape.

The same notebook becomes the capstone log.

Config

• Write the goal in one sentence.
• Name the input and the allowed output.
• Save the trace next to the result.

Troubleshooting

• The answer looks fluent and is wrong. Check whether a source passage actually contains the claim.
• The loop never stops. Set a step cap and stop when the tool result repeats.

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