code: function addEventKeys(props, data) {
    const hasEventKeyAccessor = !!props.eventKey;
    const eventKeyAccessor = getEventKey(props.eventKey);
    return data.map((datum) => {
      if (datum.eventKey !== undefined) {
        return datum;
      } else if (hasEventKeyAccessor) {
        const eventKey = eventKeyAccessor(datum);
        return eventKey !== undefined ? assign({ eventKey }, datum) : datum;
      } else {
        return datum;
      }
    });
  }
docs: Returns data with an eventKey prop added to each datum