Helper Decomposition

Real-world functions often start simple then grow unwieldy. Helper decomposition is the practice of breaking large functions into smaller, focused helpers. Each helper does one thing well, making code easier to test, debug, and maintain. This pattern is essential in data engineering. An ETL function that extracts, validates, transforms, and loads data should not be a single 200-line function. Breaking it into helpers makes each step testable and the flow clear. When a bug appears, you can quickly identify which helper is responsible. The principle is "single responsibility" - each function should do one thing and do it well. A function called validate_user_age should only validate age, not also format names or calculate statistics. When functions have single responsibilities, they become r