@staticmethod
def modify_snapshot_prefix(snapshot_name, manage=False, unmanage=False):
    """Modify a Snapshot prefix on PowerMax/VMAX backend.

        Prepare a snapshot name for manage/unmanage snapshot process either
        by adding or removing 'OS-' prefix.

        :param snapshot_name: the old snapshot backend display name
        :param manage: (bool) if the operation is managing a snapshot
        :param unmanage: (bool) if the operation is unmanaging a snapshot
        :return: snapshot name ready for backend PowerMax/VMAX assignment
        """
    new_snap_name = None
    if manage:
        new_snap_name = '%(prefix)s%(snapshot_name)s' % {'prefix': 'OS-',
            'snapshot_name': snapshot_name}
    if unmanage:
        snap_split = snapshot_name.split('-', 1)
        if snap_split[0] == 'OS':
            new_snap_name = snap_split[1]
    return new_snap_name
