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Intermediate 18 min readModule: Module 6: Functions, Args, Kwargs & Lambda

*args, **kwargs, Lambdas & Type Hints

Build flexible functions with variable positional and keyword arguments, and add static type hints.

What You Will Learn in This Lesson

  • Variable positional arguments (*args) and keyword arguments (**kwargs)
  • Anonymous lambda functions for sorting and mapping
  • Type hints (def fn(x: int) -> str) and verification with mypy

Introduction & Core Concept

Functions in Python support flexible argument passing mechanisms and optional static type hints.
WHY DOES THIS MATTER IN THE REAL WORLD?

Type hints in modern Python power frameworks like FastAPI and Pydantic for automatic data validation.

Type-Hinted Function with **kwargs

python
python
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def build_profile(user_id: str, **metadata: str) -> dict[str, str]:
    profile = {"id": user_id}
    profile.update(metadata)
    return profile
 
user = build_profile("usr_101", name="Alex", role="Engineer")
print("Profile:", user)

Line-by-Line Technical Breakdown

1Type hints do not impact runtime performance; they are used by IDEs and linters.

Try It Yourself (Interactive Editor)

Modify the code in real-time and click Run to test live browser output and console logs.

Intelligent Code Runner & Live Sandbox[PYTHON]
PYTHON SOURCE EDITOR
Interactive Live Code

Industry Best Practices & Professional Standards

  • Always include type hints on public utility functions.

Lesson Summary & Core Takeaways

  • Type hints and flexible arguments make Python codebases clean and scalable.