Sets are unordered collections of unique values: {1, 2, 3}. Use add() and remove() to modify. Set operations union |, intersection &, and difference - work like in math. Great for removing duplicates.
Sets — Unique Values
a = {1, 2, 3, 4}
b = {3, 4, 5, 6}
print(a | b) # union
print(a & b) # intersection
print(a - b) # difference
print(a ^ b) # symmetric diff
a.add(99)
a.discard(1)
print(2 in a) # True