def container
      @opf_path = opf_path
      tmplfile = File.expand_path('./xml/container.xml.erb', ReVIEW::Template::TEMPLATE_DIR)
      tmpl = ReVIEW::Template.load(tmplfile)
      tmpl.result(binding)
    end
def container
      @opf_path = opf_path
      tmplfile = File.expand_path('./xml/container.xml.erb', ReVIEW::Template::TEMPLATE_DIR)
      tmpl = ReVIEW::Template.load(tmplfile)
      tmpl.result(binding)
    end
Return container content.