@hep.over('<STR_LIT>', '<STR_LIT>')<EOL>@utils.for_each_value<EOL>def book_series(self, key, value):
return {<EOL>'<STR_LIT:title>': value.get('<STR_LIT:a>'),<EOL>'<STR_LIT>': value.get('<STR_LIT:v>'),<EOL>}<EOL>
Populate the ``book_series`` key.