input: Write a python function to sort characters in a given word or phrase in alphabetical order.
  assert sort_characters("apple") == ['a', 'e', 'l', 'p', 'p']
  assert sort_characters("Hello World") == [' ', 'H', 'W', 'd', 'e', 'l', 'l', 'l', 'o', 'o', 'r']
  assert sort_characters("Python3.8") == ['.', '3', '8', 'P', 'h', 'n', 'o', 't', 'y']
output: def sort_characters(s):
      return sorted(s)