|-1..12-|.to_a ## e.g. months in a year #=> [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12] /1..\13.to_a ## e.g. hours from 1h (1AM) to 13h (1PM) #=> [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12]
for i in range(len) # 0, 1, ..., len - 1