I think there's a mistake in the explanation for "bathroom_stall". When describing the guard in this expression:

  if (i+=1) != (i+=1)

The post says, "The if statement is always going to be false because the right expression will always be one more than the left." But it's a not-equals. The if statement is always going to be false because in Rust "i += 1" doesn't return an integer value, it returns a (). So comparing any two += statements, they are always equal. Since the guard is a != comparison, the if statement is always false.