If an operation succeeds, it should return a value; if it fails, it should return a different value.

A common pattern is to return a tuple or an object that contains both the result and a status flag. For example, in Python you could return (True, result) on success and (False, error_message) on failure. Alternatively, use exceptions for error paths and return the value only on success. This makes the caller’s logic clear: check the status before using the result.