input: Write a function to generate a Python program to sort a list of numbers. The function should return the sorted list. If the input array is empty, the function should return an empty list.
  assert sort_list([4, 2, 6, 7, 1])==[1, 2, 4, 6, 7]
  assert sort_list([])==[]
output: def sort_list(arr):
      return sorted(arr)