Slice Notation with Python

I recently began working in "Grokking Algorithms" by Aditya Y. Bhargava. Just four chapters in, and I have learned so much (and remembered so much from my long-forgotten math classes) that I MUST share the experience with y'all, but that will have to be a later post because: PYTHON. SLICES.

The principles for creating a substring from a string in Python apply to solving the question:

How do I filter my string ONLY to see what I am looking for in this string?

• One way to do string manipulation in Python is by implementing slice() notation.
• Slice() notation is a way to pull specific items into a smaller string from a larger one.
• You pull specific items by setting the start point and endpoint for the items you are looking for, then specifying a pattern using step.
• You specify the location of the items you are manipulating by calling the start and end index.
• By specifying the start, end, and step, you can isolate items by placing them into a new string.

By implementing slice() notation, I wrote recursive functions that found the number of items in a list and the max item of a list. 

A Note: the exercises for this chapter are not working with strings but arrays. I found reading "How to Substring a String in Python"  on FreeCodeCamp very helpful. By starting with strings, I was able to then manipulate arrays with the help of this Stack Overflow post.