code: 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]);
      }
  }
docs: Bind individual rule
  
  @private
  @param {Object} conf - breakpoint rules
  @param {Array} [conf.args] - callback arguments
  @param {Function} conf.callback
  @param {boolean} [conf.each=false] - execute for each matching breakpoint
  @param {boolean} [conf.init=true] - check event on load
  @param {number} [conf.max] - maximum breakpoint value
  @param {number} [conf.min] - minimum breakpoint value
  @param {boolean} [conf.once=false] - only execute the callback once
  @param {Object} [conf.scope] - callback scope
  @param {number} [conf.size] - specific breakpoint value
  @param {boolean} [conf.watch=true] - check event on screen resize
  @param {string} [conf.namespace] - namespace the event