Sublists and Substrings

Given a list or a string, it is easy to extract just part of the list or part of the string.

• seq[start:after] extracts all the elements starting at position start and finishing immediately before position after.
• seq[start:] extracts all the elements starting at position start and finishing at the end of the list/string.
• seq[:n] extracts all the elements before position n. That is, it gives you the first n elements of the sequence.

There are many other ways to extract sublists and substrings, but these are the ones you'll need the most.