input: Write a function to check if any two numbers from a given list sum up to a given target number. The function should return True if such a pair exists, otherwise False. If the input list is empty, the function should return False.
  assert check_sum([1, 2, 3, 4], 7) == True
  assert check_sum([1, 2, 3, 4], 8) == False
  assert check_sum([], 5) == False
  assert check_sum([3, 1, 4, 1, 5], 5) == True
  assert check_sum([1, 2, 3, 4, 5], 10) == False
output: def check_sum(nums, target):
      seen = set()
      for num in nums:
          if target - num in seen:
              return True
          seen.add(num)
      return False