<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def command_str(self):
 """get command to execute as string properly escaped :return: string """

        if isinstance(self.command, six.string_types):
            return self.command
        return ' '.join(map(six.moves.shlex_quote, self.command))