input: Write a function to determine if any two numbers from a given list sum up to a specified target. If such a pair exists, 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, 5], 9)==True
  assert check_sum([10, 20, 30, 40], 60)==False
  assert check_sum([3, 1, 5, 8], 6)==True
  assert check_sum([], 10)==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