code: function (context) {
  	    var maskedContext = this._maskContext(context);
  	    if (process.env.NODE_ENV !== 'production') {
  	      var Component = this._currentElement.type;
  	      if (Component.contextTypes) {
  	        this._checkContextTypes(Component.contextTypes, maskedContext, ReactPropTypeLocations.context);
  	      }
  	    }
  	    return maskedContext;
  	  }
docs: Filters the context object to only contain keys specified in
  `contextTypes`, and asserts that they are valid.
  
  @param {object} context
  @return {?object}
  @private