This symbol is a type alias.
Source:
JsonableType = Union[
bool,
bytes,
float,
int,
tfx.utils.json_utils.Jsonable,
google.protobuf.message.Message,
str,
Type,
list[Union[bool, bytes, float, int, tfx.utils.json_utils.Jsonable, google.protobuf.message.Message, str, Type]],
dict[tfx.v1.dsl.io.fileio.PathType
, Union[bool, bytes, float, int, tfx.utils.json_utils.Jsonable, google.protobuf.message.Message, str, Type, list[Union[bool, bytes, float, int, tfx.utils.json_utils.Jsonable, google.protobuf.message.Message, str, Type]]]]
]