input: Write a python function to check if any two numbers in a list add up to a target value.
  assert check_sum([1, 2, 3, 4, 5], 8) == True
  assert check_sum([1, 2, 3, 4, 5], 10) == False
  assert check_sum([0, -1, 2, -3, 1], -2) == True
output: def check_sum(lst, target):
      seen = set()
      for num in lst:
          if target - num in seen:
              return True
          seen.add(num)
      return False