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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def bindmount(self, mountpoint):
 """Bind mounts the volume to another mountpoint. Only works if the volume is already mounted. :raises NotMountedError: when the volume is not yet mounted :raises SubsystemError: when the underlying command failed """


        if not self.mountpoint:
            raise NotMountedError(self)
        try:
            _util.check_call_(['mount', '--bind', self.mountpoint, mountpoint], stdout=subprocess.PIPE)
            if 'bindmounts' in self._paths:
                self._paths['bindmounts'].append(mountpoint)
            else:
                self._paths['bindmounts'] = [mountpoint]
            return True
        except Exception as e:
            logger.exception("Error bind mounting {0}.".format(self))
            raise SubsystemError(e)