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Getting Started with Python · Lesson 7

Getting Help with Help and Documentation

Python can inspect many objects at runtime.

ConceptWorked examplePracticeKnowledge check
Textbook walkthrough

Getting Help with Help and Documentation

Python can inspect many objects at runtime. help(object) displays documentation, dir(object) lists available attribute names, and type(object) identifies the object type. These tools are most useful when paired with a concrete question: what arguments does this function accept, what method exists on this object, and what type did my code actually produce?

Learning goal: explain why Getting Help with Help and Documentation behaves this way, apply it to a small example, and verify the result independently. Begin by being able to justify this first step: Use type() to identify an unfamiliar value.

Deeper walkthrough

Read Getting Help with Help and Documentation as a mechanism, not a recipe

Treat this as a sequence of observable decisions rather than one opaque command. Stage 1: Use type() to identify an unfamiliar value. Stage 2: Use dir() to discover attributes and methods. Stage 3: Use help() on a function/class/module to inspect its interface and documentation. Final checkpoint: Test the smallest documented example and then adapt it to your data.

Mechanism

Follow the transformation

Use type() to identify an unfamiliar value.

Use dir() to discover attributes and methods.

Use help() on a function/class/module to inspect its interface and documentation.

Evidence

Know what would convince you

  • Trace a tiny input by hand and compare the runtime result.
  • Inspect type, value/shape and any mutation/side effect explicitly.
Useful distinctionInput: Objects/values supplied to the operation.
How it works

Trace the mechanism step by step

  1. Use type() to identify an unfamiliar value.
  2. Use dir() to discover attributes and methods.
  3. Use help() on a function/class/module to inspect its interface and documentation.
  4. Inspect a callable signature before guessing arguments.
  5. Test the smallest documented example and then adapt it to your data.
Worked demonstration

Runtime help

# Step 1 — Compute the right-hand expression and store its result in `values` for the next step.
values = [3, 1, 2]
# Step 2 — Display the current value explicitly so the result/state can be inspected during execution.
print(type(values).__name__)
# Step 3 — Display the current value explicitly so the result/state can be inspected during execution.
print("append" in dir(values))
# Step 4 — Call the function with these arguments and use its returned value or side effect in the workflow.
help(list.append)
Expected / illustrative result
The object is a list, append is one of its methods, and help describes how list.append modifies the list.
Interpret the result.

For Getting Help with Help and Documentation, trace the specific input through the mechanism above and independently verify one returned value, state change or side effect.

Distinctions & related ideas

Place the concept correctly

InputObjects/values supplied to the operation.
StateNames or mutable objects that may change during execution.
OutputReturned value, side effect, file, plot or exception to inspect.
Use deliberately

When it is appropriate

Use Getting Help with Help and Documentation when it answers a defined question in Getting Started with Python and its inputs/assumptions match the current data or program state.

Boundary conditions

When to stop or reconsider

Reconsider Getting Help with Help and Documentation when the required information is unavailable, the operation would violate a validation/data boundary, or a simpler operation answers the question more transparently.

Common mistakes

Failure modes to recognise

  • Running the operation on the wrong object/type or in the wrong environment.
  • Inferring correctness from “no exception” without checking the produced value/state.
  • Hiding a boundary case instead of making its behaviour explicit.
Verification

How to check the result

  • Trace a tiny input by hand and compare the runtime result.
  • Inspect type, value/shape and any mutation/side effect explicitly.
  • Run an edge or invalid case and confirm the exception/behaviour is deliberate.
Hands-on practice

Demonstrate understanding

Try this:

Construct a tiny example of Getting Help with Help and Documentation. First use type() to identify an unfamiliar value. Then use dir() to discover attributes and methods. Predict the result before execution and explain one boundary or failure case.

Use the smallest values that expose the language rule. Write the expected value and type first, then compare the actual state/output with that prediction.
Knowledge check

Check reasoning, not memorisation

Which approach best demonstrates understanding of Getting Help with Help and Documentation?

Quick reference

Remember the logic

Step 1Use type() to identify an unfamiliar value.
Step 2Use dir() to discover attributes and methods.
Step 3Use help() on a function/class/module to inspect its interface and documentation.
Step 4Inspect a callable signature before guessing arguments.
Lesson summary

What to remember

  • Python can inspect many objects at runtime. help(object) displays documentation, dir(object) lists available attribute names, and type(object) identifies the object type. These tools are most useful when paired with a concrete question: what arguments does this function accept, what method exists on this object, and what type did my code actually produce?
  • Use type() to identify an unfamiliar value.
  • Running the operation on the wrong object/type or in the wrong environment.
  • Trace a tiny input by hand and compare the runtime result.