520     struct attribute_size  struct
525     struct attribute_size<optional<Attribute> >  struct
527         typedef typename attribute_size<Attribute>::type type;
529         static type call(optional<Attribute> const& val)  in call()
550     struct attribute_size<variant<BOOST_VARIANT_ENUM_PARAMS(T)> >  struct
552         typedef std::size_t type;
554         static type call(variant<BOOST_VARIANT_ENUM_PARAMS(T)> const& val)  in call()
561     struct attribute_size<iterator_range<Iterator> >  struct
564             difference_type type;
566         static type call(iterator_range<Iterator> const& r)  in call()
573     struct attribute_size<unused_type>  struct
575         typedef std::size_t type;
577         static type call(unused_type)  in call()