code: function elasticsearch (elasticsearchClient) {
      // set client if passed
      if (defined(elasticsearchClient)) {
          // set client on model - throws error on invalid client
          this.elasticsearchClient = this.requireValidElasticsearchClient(elasticsearchClient)
          // return model when setting value
          return this
      }
      // if client is set to true then check if global client exists
      if (this.elasticsearchClient === true) {
          // if global client is set then set it locally
          this.elasticsearchClient = this.requireValidElasticsearchClient(ImmutableCoreModel.elasticsearchGlobal())
      }
      // return current client setting
      return this.elasticsearchClient
  }
docs: @function elasticsearch
  
  get/set the elasticsearch client for a model
  
  @param {object|undefined} elasticsearchClient
  
  @returns {boolean|object}
  
  @throws {Error}