docs: function(spaces) {
  			var prop, def, metas = document.querySelectorAll('meta[name]');
  			Array.forEach(metas, function(meta) {
  				prop = meta.getAttribute('name');
  				spaces.forEach(function(ns) {
  					if (prop.startsWith(ns + '.')) {
  						def = gui.Object.lookup(prop);
  						if (gui.Type.isDefined(def)) {
  							gui.Object.assert(prop,
  								gui.Type.cast(meta.getAttribute('content'))
  							);
  						} else {
  							console.error('No definition for "' + prop + '"');
  						}
  					}
  				});
  			});
  		}