code: def decorated_filename(filename, stat):
      
      mode = stat[0]
      if mode_isdir(mode):
          return DIR_COLOR + filename + END_COLOR + '/'
      if mode_issymlink(mode):
          return filename + '@'
      if filename.endswith('.py'):
          return PY_COLOR + filename + END_COLOR
      return filename
docs: Takes a filename and the stat info and returns the decorated filename.
         The decoration takes the form of a single character which follows
         the filename. Currently, the only decoration is '/' for directories.