Definition: You are given a list of integers and an integer target, return a list of a pair of numbers in any order such that they add up to target. If there is no such pair of numbers, then return an empty list
Input: [38, 44, 45, 4, 43, 40, 41, 42, 48, 10, 32, 3, 47, 20, 17, 28, 31, 34, 27, 2], target=21
Output:
[4, 17]