input: Write a function to sort an array in ascending order.
  
  def sort_ascending(array):
    array.sort()
    return array
  
  assert sort_ascending([10, 3, 9, 1, 15, 2])==[1, 2, 3, 9, 10, 15]
  assert sort_ascending([5, 2, 7, 1, 9])==[1, 2, 5, 7, 9]
  assert sort_ascending([0, 0, 0, 0])==[0, 0, 0, 0]
  assert sort_ascending([])==[]
  assert sort_ascending([1])==[1]
output: def sort_ascending(array):
    array.sort()
    return array