code: func (r *Route) Path(tpl string) *Route {
  	r.err = r.addRegexpMatcher(tpl, regexpTypePath)
  	return r
  }
docs: // Path -----------------------------------------------------------------------
  // Path adds a matcher for the URL path.
  // It accepts a template with zero or more URL variables enclosed by {}. The
  // template must start with a "/".
  // Variables can define an optional regexp pattern to be matched:
  //
  // - {name} matches anything until the next slash.
  //
  // - {name:pattern} matches the given regexp pattern.
  //
  // For example:
  //
  //     r := mux.NewRouter()
  //     r.Path("/products/").Handler(ProductsHandler)
  //     r.Path("/products/{key}").Handler(ProductsHandler)
  //     r.Path("/articles/{category}/{id:[0-9]+}").
  //       Handler(ArticleHandler)
  //
  // Variable names must be unique in a given route. They can be retrieved
  // calling mux.Vars(request).