for-in loops also give us the flexibility to choose how we want to iterate over a sequence with the stride() function:

stride(from: a, to: b, by: c)

Notice, in order to use the stride() function we have to supply 3 values separated by commas. When we use it in a for-in loop:

for num in stride(from: 0, to: 6, by: 2) {
  print(num)
}

It prints out:

0
2
4

The values we provide functions are called arguments. In each argument there is an argument label, e.g. from:, to:, by:. We’ll cover more about how functions work in a later lesson, but here’s a sneak peek:

• The first argument, from: 0 is the starting number of the sequence (0).
• The second argument, to: 6 is the end of the sequence (6). But notice, we didn’t print out 6 which means this end number is not included.
• The third argument, by: 2 determines how much to increment (or decrement if we use a negative number) during each iteration. Here’s how the value of num changes in the loop: