code: function link(stateName, params) {
      const state = leafStates[stateName]
      if (!state) throw new Error('Cannot find state ' + stateName)
  
      const interpolated = interpolate(state, params)
      const uri = util.normalizePathQuery(interpolated)
  
      return isHashMode()
        ? '#' + options.hashPrefix + uri
        : uri
    }
docs: /*
  Compute a link that can be used in anchors' href attributes
  from a state name and a list of params, a.k.a reverse routing.