Calling and Storing

Defining a function creates it but does not execute it. The function body only runs when you explicitly call the function by writing its name followed by parentheses containing any required arguments. You can call a function as many times as needed, and each call is independent. The results can be used directly, stored in variables, or passed to other functions. Functions Calling Functions Functions can call other functions. This is how you build complex programs from simple, well-tested pieces. Each function handles one specific task, and higher-level functions combine them to accomplish larger goals. This approach is called functional decomposition, and it is fundamental to writing maintainable software. Real Data Pipeline Pattern Professional data engineers structure ETL pipelines as ch