code: def custom_object_prefix_lax(instance):
      
      if (instance['type'] not in enums.TYPES and
              instance['type'] not in enums.RESERVED_OBJECTS and
              not CUSTOM_TYPE_LAX_PREFIX_RE.match(instance['type'])):
          yield JSONError("Custom object type '%s' should start with 'x-' in "
                          "order to be compatible with future versions of the "
                          "STIX 2 specification." % instance['type'],
                          instance['id'], 'custom-prefix-lax')
docs: Ensure custom objects follow lenient naming style conventions
      for forward-compatibility.