Functions & basics
Reusable building blocks — parameters, returns, scope, and clear function design.
Chain Generators with yield from in Python
Combine multiple generators into one seamless sequence using the `yield from` delegation syntax in Python.
def numbers():
yield 1
yield 2
yield 3
def letters():
yield 'a'
yield 'b'
yield 'c'
def combined():
yield from numbers()
yield from letters()
if __name__ == "__main__":
print(list(combined()))Format CLI help text in Python
Build a readable usage string for a command-line tool, aligning flags and wrapping descriptions with the textwrap module.
import textwrap
def format_help(command_name: str, description: str, options: list[tuple[str, str]]) -> str:
"""Format CLI help text into a readable usage string."""
header = f"Usage: {command_name} [OPTIONS]"
lines = [header, "", description, "", "Options:"]
for flag, help_text in options:
…How to Add a Dry Run Flag to a Python CLI Command
Build a Python CLI command with a --dry-run flag that previews actions and exits before making real changes.
import argparse
import sys
def main():
parser = argparse.ArgumentParser(description="Sample CLI command with dry-run flag")
parser.add_argument("--name", required=True, help="Name to greet")
parser.add_argument("--dry-run", action="store_true", dest="dry_run",
help="Show what would…How to Pipe Data Through a List of Transform Functions in Python
Applies a sequence of functions to an initial value using functools.reduce, creating a reusable pipe utility.
from functools import reduce
def pipe(data, *transforms):
return reduce(lambda value, func: func(value), transforms, data)
def double(x):
return x * 2
def add_one(x):
return x + 1
def to_string(x):
return f"Result: {x}"
if __name__ == "__main__":
initial = 5
result = pipe(initial, double, …How to Return Multiple Values from a Python Function
This code demonstrates how a Python function can return multiple values as a tuple, and how to unpack that tuple into individual variables.
def get_user_stats(name, score, level):
"""Return multiple values as a tuple."""
return name, score, level
if __name__ == "__main__":
result = get_user_stats("Alice", 95, 3)
print(result)
print(type(result))
# Unpacking into individual variables
player_name, player_score, player_level…How to Use the if __name__ == '__main__' Guard in Python
This code defines reusable functions and uses the standard main guard to run them only when the script is executed directly, not when imported.
def greet(name: str) -> str:
"""Return a friendly greeting."""
return f"Hello, {name}!"
def get_planet() -> str:
"""Return the name of our planet."""
return "Earth"
if __name__ == "__main__":
user = "Dorothy"
print(greet(user))
print(f"We live on {get_planet()}.")How to Write a Normalize Function with Default Parameters in Python
Define a reusable normalize function with configurable default parameters for lowercase conversion, whitespace stripping, and punctuation removal.
def normalize(text, lowercase=True, strip_whitespace=True, remove_punctuation=False):
"""Normalize a string based on configurable options."""
if lowercase:
text = text.lower()
if strip_whitespace:
text = text.strip()
if remove_punctuation:
text = ''.join(char for char in text if…Browse by section
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Functions & basics — Python code examples
What you will find here
This page collects functions & basics snippets — short, copy-ready Python you can paste into our free online IDE and run without installing anything. Each sample includes a plain-English explanation and the full source code.
Samples vs tutorials and challenges
Samples are quick reference — one concept per page. For step-by-step teaching, use our Python tutorials. To test yourself, try quizzes or coding challenges. Clean up style with the Python formatter.