code: function(conn, parent, config) {
    SubQuery.super_.call(this, conn, config);
    this._parent = parent;
  }
docs: /*-------------------------------------------- 
  SubQuery object for representing child relationship query
  
  @protected
  @class Query~SubQuery
  @extends Query
  @param {Connection} conn - Connection object
  @param {Query} parent - Parent query object
  @param {Object} config - Sub query configuration