a = [1, 2, 3, 4, 5] a.delete_at(2) a # => [1, 2, 4, 5]
a = [1, 2, 3, 4, 5] a.shift() a # => [2, 3, 4, 5]
a = [1, 2, 3, 4, 5] a.pop() a # => [1, 2, 3, 4]
