- Is the programming focused on doing membership tests? An example of this is a collection of valid input values. When the user enters something that's in the collection, their input is valid, otherwise it's invalid.
Simple membership suggests using a set:
valid_inputs = {"yes", "y", "no", "n"}
answer = None
while answer not in valid_inputs:
answer = input("Continue? [y, n] ").lower()
A set holds items in no particular order. Once an item is a member, we can't add it again:
>>> valid_inputs = {"yes", "y", "no", "n"}
>>> valid_inputs.add("y")
>>> valid_inputs
{'no', 'y', 'n', 'yes'}
We have created a set, valid_inputs, with four distinct string items. We can't add another y to a set which already contains y. The contents ...
