subject = XML.string_from_xpath("//Subject", doc)
salmon = XML.string_from_xpath(~s{//Link[@rel="salmon"]/@href}, doc)
subscribe_address = XML.string_from_xpath(~s{//Link[@rel="http://ostatus.org/schema/1.0/subscribe"]/@template}, doc)
subject = XML.string_from_xpath("//Subject", doc)
salmon = XML.string_from_xpath(~s{//Link[@rel="salmon"]/@href}, doc)
subscribe_address = XML.string_from_xpath(~s{//Link[@rel="http://ostatus.org/schema/1.0/subscribe"]/@template}, doc)