def filter_entity(entity_ref):
    """Filter out private items in an entity dict.

    :param entity_ref:  the entity dictionary. The 'dn' field will be removed.
        'dn' is used in LDAP, but should not be returned to the user.  This
        value may be modified.

    :returns: entity_ref

    """
    if entity_ref:
        entity_ref.pop('dn', None)
    return entity_ref