Post 3

I continued work on adding methods to existing data structures, and improving others.

• Added list repeat (1888). Fixed warnings from a couple of other functions
• Fixed an issue to disallow zero step in list, string slicing (1879).
• Completed work for 1845 - there was an issue in popping from nested iterables

For the next week, I plan to work on known issues. This includes

• Supporting nested tuples (1886)
• List index with optional arguments