docs: function routeFromRel (route, rel) {
      // if rel is empty string then this is route
      if (rel.length === 0) {
          // set root flag on route
          route.root = true
          // return route
          return route
      }
      // if rel is above root this is error
      assert.ok(!rel.match(/^\./), 'relative path above app root: '+rel)
      // split rel into directories
      var dirs = rel.split('/')
      // get next route node for each dir in rel path
      _.each(dirs, dir => {
          // create sub node if it does not exists
          if (!route.routes) {
              route.routes = {}
          }
          // create new entry for dir if it does not exist
          if (!route.routes[dir]) {
              route.routes[dir] = {}
          }
          // switch context
          route = route.routes[dir]
      })
      // return resolved route
      return route
  }