Function Basics in Python
From the Python cheat sheet · Functions · verified Jul 2026
Function Basics
Define functions with parameters, defaults, and return values.
python
def greet(name, greeting="Hello"):
"""Return a greeting string."""
return f"{greeting}, {name}!"
result = greet("Alice")
result = greet("Bob", greeting="Hi")💡 Use / to mark positional-only params, * to mark keyword-only params
⚡ Functions can return multiple values as a tuple — unpack with a, b = func()
📌 Default arguments are evaluated once — never use mutable defaults like def f(x=[])
🟢 Add docstrings as the first line in a function for documentation
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