Get an iterator of JFSFolder() from the given mountPoint.

        "mountPoint" may be either an actual mountPoint element from JFSDevice.mountPoints{} or its .name.

def folders(self, mountPoint):
        """Get an iterator of JFSFolder() from the given mountPoint.

        "mountPoint" may be either an actual mountPoint element from JFSDevice.mountPoints{} or its .name. """
        if isinstance(mountPoint, six.string_types):
            # shortcut: pass a mountpoint name
            mountPoint = self.mountPoints[mountPoint]
        try:
            return [JFSFolder(f, self, parentpath='%s/%s' % (self.path, mountPoint.name)) for f in self.contents(mountPoint).folders.iterchildren()]
        except AttributeError as err:
            # no files at all
            return [x for x in []]