input: Write a python function to find a pair of numbers in a list that sum up to a given number.
  assert find_sum_pair([1, 2, 3, 4, 5], 9) == [4, 5]
  assert find_sum_pair([10, 20, 10, 40, 50, 60, 70], 50) == [10, 40]
  assert find_sum_pair([0, -1, 2, -3, 1], -2) == [-1, -1]
output: def find_sum_pair(lst, target):
      seen = {}
      for num in lst:
          complement = target - num
          if complement in seen:
              return [complement, num]
          seen[num] = True