Conditional routing for Mithril

mithril-conditional-route.js

;(function (mod) {
  if (typeof module === "object" && module != null && module.exports) {
    // Node
    module.exports = mod
  } else if (typeof define === "function" && define.amd) {
    // AMD
    define("mithril-configure", function () { return mod })
  } else if (typeof exports === "object" && exports != null) {
    // Other CommonJS
    exports.init = mod
  } else {
    // Browser - just initialize it immediately (common use case)
    mod(m)
  }
})(function (m) {
  if (typeof m !== "function" || typeof m.route !== "function") {
    throw new TypeError("Expected a Mithril instance")
  }
  if (!m.route.configure) m.route.configure = function (condition, run) {
    var old = m.route
    var check = m.route = function (route) {
      if ({}.toString.call(route) !== "[object String]" || !condition(route)) {
        return old.apply(this, arguments)
      } else {
        return run(old, route)
      }
    }
  
    // So the properties are still accessible (and doesn't break Mithril)
    for (var i in old) if ({}.hasOwnProperty.call(old, i)) {
      check[i] = old[i]
    }
  
    // So it's easy to restore
    return function () {
      if (m.route !== check) {
        throw new ReferenceError("m.route no longer references this checker!")
      }
      m.route = old
    }
  }
  return m
});

Can you explain how to use this? Tks