GrssFeedAtomFormatter — able to format a feed in Atom
GObject ╰── GrssFeedFormatter ╰── GrssFeedAtomFormatter
GrssFeedAtomFormatter is an implementation of GrssFeedFormatter able to handle Atom format
GrssFeedAtomFormatter * grss_feed_atom_formatter_new ();
#define GRSS_FEED_ATOM_FORMATTER_TYPE (grss_feed_atom_formatter_get_type())