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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 unmount(self):
 """Unmounts the sftp system if it's currently mounted."""

        if not self.mounted:
            return

        # Try to unmount properly.
        cmd = 'fusermount -u %s' % self.mount_point_local
        shell_exec(cmd)

        # The filesystem is probably still in use.
        # kill sshfs and re-run this same command (which will work then).
        if self.mounted:
            self._kill()
            shell_exec(cmd)

        self._mount_point_local_delete()