Section 7. User Defined Functions
The recommendation is that you view the videos listed below in sequence
  1. Why we have Python functions >>
  2. Python User Defined Function >>
  3. How to design a Python function >>
  4. Python Function with arguments and no return value >>
  5. Python Function with no arguments but return value >>
  6. Python Function with no arguments and no return value >>
  7. Python Keyword Arguments for functions >>
  8. Python Default Arguments for functions >>
  9. Local and Global Variable Scope >>
  10. Lifetime of Variables >>
  11. In functions do not directly access global variable >>
  12. Python Parameter Passing Mechanism >>