code: function api_ready(ready) {
      var self = this
  
      if ('function' === typeof ready) {
        setImmediate(function register_ready() {
          if (root$.private$.ge.isclear()) {
            execute_ready(ready.bind(self))
          } else {
            root$.private$.ready_list.push(ready.bind(self))
          }
        })
      }
  
      return self
    }
docs: useful when defining services! note: has EventEmitter.once semantics if using .on('ready',fn) it will be be called for each ready event