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Manuals / Python / Chapter 4

B · Structure · beginner · Week 2 · Chapter 4 of 13

Functions, modules & packages

def, return, default args, type hints lite, import, project layout with src/ and tests/.

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Step 1 of 3

Write functions

Pure functions first — same input, same output, no side effects. Easier to test.

Write functionsDrag stickies · tap for tips
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Example

def is_valid_email(s: str) -> bool:
    return "@" in s and "." in s.split("@")[-1]

Do this now

Write is_valid_email(s), normalize_phone(s), build_url(base, path).

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Chapter learning outcomes
  • Functions and returns
  • Default arguments
  • Modules and imports
  • Type hints lite

Clear these before you leave

Side quest

Config loader

load_config(path) → dict with try/except for missing file.