input: Write a python function to compare two strings lexicographically.
  assert stringCompare("apple", "banana") == -1
  assert stringCompare("grape", "apple") == 1
  assert stringCompare("orange", "orange") == 0
output: def stringCompare(str1, str2):
      if str1 < str2:
          return -1
      elif str1 > str2:
          return 1
      else:
          return 0