If the external id is precised, it will be used to dynamically retrieves
the URL when printing this content. This is useful for some source that
change the content's URL (like soundcloud).

Fuck soundcloud.

It's like I used to think there will be only one query for ever.

!get iterates on the results of a repeated query instead of just doing a
stupid random.

Everyone in is namespace and the subroutines will be safe.