code: function resolveURL (args) {
      var from = args.from;
      var to = args.to;
      var next = args.next;
  
      if (!isSupportedURL(from) && !isSupportedURL(to)) {
        // It's not a supported URL, so let some other plugin resolve it
        return next();
      }
  
      if (from) {
        return resolveUrl(from, to);
      }
      else {
        return to;
      }
    }
docs: Resolves a URL, relative to a base URL.
  
  @param {?string} args.from
  The base URL to resolve against. If unset, then {@link args.to} MUST be absolute.
  
  @param {string} args.to
  The URL to resolve. This may be absolute or relative. If relative, then it will be resolved
  against {@link args.from}
  
  @param {function} args.next
  Calls the next plugin, if the file path is not a URL.
  
  @returns {string|undefined}