We can also use a new operator called the combined comparison operator to compare two Ruby objects. The combined comparison operator looks like this: <=>. It returns 0 if the first operand (item to be compared) equals the second, 1 if the first operand is greater than the second, and -1 if the first operand is less than the second.
A block that is passed into the sort method must return either1, 0, or -1. It should return -1 if the first block parameter should come before the second, 1 if vice versa, and 0 if they are of equal weight, meaning one does not come before the other (i.e. if two values are equal)