new_contents: lass ImplementStrStr:
      def strStr(haystack: str, needle: str) -> int:
          # Base conditions
          if haystack is None or needle is None:
              return -1
          # Special case
          if haystack == needle:
              return 0
          # Length of the needle
          needleLength = len(needle)
          # Loop through the haystack and slide the window
          for i in range(len(haystack) - needleLength + 1):
              if haystack[i:i + needleLength] == needle:
                  return i
          return -1
  
subject: Create index_of_string.py