code: def has_filename(self, filename):
          
          fixpath = lambda path: osp.normcase(osp.realpath(path))
          for index, finfo in enumerate(self.data):
              if fixpath(filename) == fixpath(finfo.filename):
                  return index
          return None
docs: Return the self.data index position for the filename.
  
          Args:
              filename: Name of the file to search for in self.data.
  
          Returns:
              The self.data index for the filename.  Returns None
              if the filename is not found in self.data.