input: Write a function to sort an array in ascending order. The function should take an array as input and return the sorted array.
  
  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, 4, 3, 2, 1]) == [1, 2, 3, 4, 5]
  assert sort_ascending([]) == []
  assert sort_ascending([3, 3, 3, 3]) == [3, 3, 3, 3]
  assert sort_ascending([7]) == [7]
output: def sort_ascending(array):
    array.sort()
    return array