input: 
  Write a function to check if any two numbers from a given list sum up to a target number. If it is possible to find such pair, return True, otherwise return False. If the list is empty, return False.
  assert check_sum([1, 2, 3, 4], 7)==True
  assert check_sum([1, 2, 3, 4], 8)==False
  assert check_sum([10, 20, 30], 50)==True
  assert check_sum([10, 20, 30], 60)==False
  assert check_sum([], 0)==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
  
output:     seen = set()
      for num in numbers:
          complement = target - num
          if complement in seen:
              return True
          seen.add(num)
      return False