input: def sort_ascending(nums):
      """Sorts a list of integers in ascending order using the selection sort algorithm.
      
      >>> sort_ascending([4, 2, 7, 1, 9])
      [1, 2, 4, 7, 9]
      >>> sort_ascending([5, -3, 0, 10, 8])
      [-3, 0, 5, 8, 10]
      >>> sort_ascending([1, 2, 3, 4, 5])
      [1, 2, 3, 4, 5]
      >>> sort_ascending([])
      []
      """
output:     for i in range(len(nums)):
          min_index = i
          for j in range(i + 1, len(nums)):
              if nums[j] < nums[min_index]:
                  min_index = j
          nums[i], nums[min_index] = nums[min_index], nums[i]
      return nums