docs: function _addRule(conf) {
      // Attach unique identifier
      conf.i = id++;
  
      // Only setup watching when enabled
      if (conf.watch !== false) {
          events.push(conf);
  
          // Only attach event once
          if (! bound) {
              const run = _run.bind(this, false, 0, null);
              bound = 1;
              events = [conf];
  
              // Attach resize event
              _win.addEventListener('resize', run);
          }
      }
  
      // Evaluate rule immediately if not disabled
      if (conf.init !== false) {
          _run(true, [conf]);
      }
  }