Write all_pairs(items) returning every pair [a, b] with a before b in the list.
all_pairs(['a', 'b', 'c']) → [['a', 'b'], ['a', 'c'], ['b', 'c']]
all_pairs([]) → []
Submit runs 4 tests, including hidden edge cases.
Each hint gives a little more help. Try on your own first.
Run your code to see the output here.