All Pairs that Sum to Target

Create a function that returns all pairs of numbers in a list that sum to a target. Sort the pairs in ascending order with respect to the smaller number, then order each pair in this order: [smaller, larger].

Examples

all_pairs([2, 4, 5, 3], 7) ➞ [[2, 5], [3, 4]]
# 2 + 5 = 7, 3 + 4 = 7

all_pairs([5, 3, 9, 2, 1], 3) ➞ [[1, 2]]

all_pairs([4, 5, 1, 3, 6, 8], 9) ➞ [[1, 8], [3, 6], [4, 5]]
# Sorted: 1 < 3 < 4; each pair is ordered [smaller, larger]

Notes

• If no pairs are found, return an empty list [].
• You are only allowed to use each number once in a pair.
• See Comments for a hint.