code: function _addFrameOutput(state, parent, property, output) {
    if(_isObject(parent)) {
      jsonld.addValue(parent, property, output, {propertyIsArray: true});
    }
    else {
      parent.push(output);
    }
  }
docs: Adds framing output to the given parent.
  
  @param state the current framing state.
  @param parent the parent to add to.
  @param property the parent property.
  @param output the output to add.