input: Write a function to check if any two numbers from a given list sum up to a target number. If there exist any two numbers that sum up to the target return True, otherwise return False. If the list is empty or contains only one element return False.
  def check_sum(numbers, target):
      for i in range(len(numbers)):
          for j in range(i+1, len(numbers)):
              if numbers[i] + numbers[j] == target:
                  return True
      return False
  assert check_sum([1, 2, 3, 4], 7)==True
  assert check_sum([1, 2, 3, 4], 8)==False
  assert check_sum([1, 2, 3, 4], 6)==True
  assert check_sum([], 4)==False
  assert check_sum([5], 5)==False
output: def check_sum(numbers, target):
      for i in range(len(numbers)):
          for j in range(i+1, len(numbers)):
              if numbers[i] + numbers[j] == target:
                  return True
      return False