numbers = [1, 2, 3]

numbers.append(4)        # [1, 2, 3, 4]
numbers.insert(1, 5)     # [1, 5, 2, 3, 4]
numbers.remove(3)        # [1, 5, 2, 4]
last_number = numbers.pop() # [1, 5, 2] (last_number = 4)

index = numbers.index(5)  # 1
count = numbers.count(2)  # 1

numbers.sort()           # [1, 2, 5]
numbers.reverse()        # [5, 2, 1]
numbers.clear()          # []