[def __foo__ Foo:__FILENAME__]

__foo__

[?__defined__
Defined conditional phrase.
[template defined_template Defined template:__FILENAME__]
[def __defined_macro__ Defined macro:__FILENAME__]
]

[?__not_defined__
Not defined conditional phrase.
[template not_defined_template Not defined template:__FILENAME__]
[def __not_defined_macro__ Not defined macro:__FILENAME__]
]