docs: def _set_magic_constants(self):
          """
          Adds magic constants to replace list.
          """
          real_path = os.path.realpath(self._source_filename)
  
          self._replace['__FILE__'] = "'%s'" % real_path
          self._replace['__ROUTINE__'] = "'%s'" % self._routine_name
          self._replace['__DIR__'] = "'%s'" % os.path.dirname(real_path)