input: Write a python function to compare the lengths of two strings.
  assert compare_length("hello", "world") == 0
  assert compare_length("short", "longer") == 2
  assert compare_length("longer", "short") == 1
output: def compare_length(str1, str2):
      if len(str1) == len(str2):
          return 0
      elif len(str1) > len(str2):
          return 1
      else:
          return 2