Section 4.1. System and User Functions
Section 4.2. Defining a Subroutine
Section 4.3. Invoking a Subroutine
Section 4.4. Return Values
Section 4.5. Arguments
Section 4.6. Private Variables in Subroutines
Section 4.7. The local Operator
Section 4.8. Variable-length Parameter Lists
Section 4.9. Notes on Lexical (my) Variables
Section 4.10. The use strict Pragma
Section 4.11. The return Operator
Section 4.12. Exercises