<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def popen(self, stdout, stderr):
 """Build popen object to run :rtype: subprocess.Popen """

        self.logger.info('Executing command: %s', self.command_str)
        return subprocess.Popen([self._executor_script], stdout=stdout, stderr=stderr)