Interestings:

• Spacing matters. Leaving a space after a minus and before a number is entirely different from putting the minus right before the number. The former is binary arithmetic and the latter is a unary operator. For example:

  [-1, 1, 2, 3].count - 1 #=> 3 (subtracting 1 from the array size)
  [-1, 1, 2, 3].count -1 #=> 1 (counting the number of occurrences of -1 in the array)