Easiest way to swap occurrences of two strings in Vim?

Question

What is the easiest way to replace all occurrences of string_a with string_b while at the same time changing anything that was already string

Answer 1

Here is how I swap two words skip & limit:

%s/skip/xxxxx/g | %s/limit/skip/g | %s/xxxxx/limit/g

Pretty sure someone could turn it into a shorter command which accepts two arguments.