myTime = (par) => {
  'use strict';

  /**
  * Format the sheet
  */
  const formatSheet = () => {
    // sort decending on start date 
    hourSheet.sort(3, false);

    // hide the technical columns
    hourSheet.hideColumns(1, 2);

    // remove any extra rows
    if (hourSheet.getLastRow() > 1 && hourSheet.getLastRow() < hourSheet.getMaxRows()) {
      hourSheet.deleteRows(hourSheet.getLastRow() + 1, hourSheet.getMaxRows() - hourSheet.getLastRow());
    }

    // set the validation for the customers
    let rule = SpreadsheetApp.newDataValidation()
      .requireValueInRange(categoriesSheet.getRange('A2:A'), true)
      .setAllowInvalid(true)
      .build();
    hourSheet.getRange('I2:I').setDataValidation(rule);

    // set the validation for the projects
    rule = SpreadsheetApp.newDataValidation()
      .requireValueInRange(categoriesSheet.getRange('B2:B'), true)
      .setAllowInvalid(true)
      .build();
    hourSheet.getRange('J2:J').setDataValidation(rule);

    // set the validation for the tsaks
    rule = SpreadsheetApp.newDataValidation()
      .requireValueInRange(categoriesSheet.getRange('C2:C'), true)
      .setAllowInvalid(true)
      .build();
    hourSheet.getRange('K2:K').setDataValidation(rule);

    if(isUseCategoriesAsCalendarItemTitle) {
      hourSheet.getRange('L2:L').setFormulaR1C1('IF(OR(R[0]C[-3]="tbd";R[0]C[-2]="tbd";R[0]C[-1]="tbd");""; CONCATENATE(R[0]C[-3];"|";R[0]C[-2];"|";R[0]C[-1];"|"))');
    }
    // set the hours, month, week and number collumns
    hourSheet.getRange('P2:P').setFormulaR1C1('=IF(R[0]C[-12]="";"";R[0]C[-12]-R[0]C[-13])');
    hourSheet.getRange('Q2:Q').setFormulaR1C1('=IF(R[0]C[-13]="";"";month(R[0]C[-13]))');
    hourSheet.getRange('R2:R').setFormulaR1C1('=IF(R[0]C[-14]="";"";WEEKNUM(R[0]C[-14];2))');
    hourSheet.getRange('S2:S').setFormulaR1C1('=R[0]C[-3]');
  };

  /**
     * Activate the synchronisation
     */
  function run() {
    console.log('Started processing hours.');

    const processCalendar = (setting) => {
      SpreadsheetApp.flush();

      // current calendar info
      const calendarName = setting.name;
      const calendarId = setting.id;

      console.log(`processing ${calendarName} with the id ${calendarId} from ${syncStartDate} to ${syncEndDate}`);

      // get the calendar
      const calendar = CalendarApp.getCalendarById(calendarId);

      // get the calendar events and create lookups
      const events = calendar.getEvents(syncStartDate, syncEndDate);
      const eventsLookup = events.reduce((jsn, event) => {
        jsn[event.getId()] = event;
        return jsn;
      }, {});

      // get the sheet events and create lookups
      const existingEvents = hourSheet.getDataRange().getValues().slice(1);
      const existingEventsLookUp = existingEvents.reduce((jsn, row, index) => {
        if (row[0] !== calendarId) {
          return jsn;
        }
        jsn[row[1]] = {
          event: row,
          row: index + 2
        };
        return jsn;
      }, {});

      // handle a calendar event
      const handleEvent = (event) => {
        const eventId = event.getId();

        // new event
        if (!existingEventsLookUp[eventId]) {
          hourSheet.appendRow([
            calendarId,
            eventId,
            event.getStartTime(),
            event.getEndTime(),
            calendarName,
            event.getCreators().join(','),
            event.getTitle(),
            event.getDescription(),
            event.getTag('Client') || 'tbd',
            event.getTag('Project') || 'tbd',
            event.getTag('Task') || 'tbd',
            (isUpdateCalendarItemTitle) ? '' : event.getTitle(),
            (isUpdateCalendarItemDescription) ? '' : event.getDescription(),
            event.getGuestList().map((guest) => guest.getEmail()).join(','),
            event.getLocation(),
            undefined,
            undefined,
            undefined,
            undefined
          ]);
          return true;
        }

        // existing event
        const exisitingEvent = existingEventsLookUp[eventId].event;
        const exisitingEventRow = existingEventsLookUp[eventId].row;

        if (event.getStartTime() - exisitingEvent[startTimeColumn - 1] !== 0) {
          hourSheet.getRange(exisitingEventRow, startTimeColumn).setValue(event.getStartTime());
        }

        if (event.getEndTime() - exisitingEvent[endTimeColumn - 1] !== 0) {
          hourSheet.getRange(exisitingEventRow, endTimeColumn).setValue(event.getEndTime());
        }

        if (event.getCreators().join(',') !== exisitingEvent[creatorsColumn - 1]) {
          hourSheet.getRange(exisitingEventRow, creatorsColumn).setValue(event.getCreators()[0]);
        }

        if (event.getGuestList().map((guest) => guest.getEmail()).join(',') !== exisitingEvent[guestListColumn - 1]) {
          hourSheet.getRange(exisitingEventRow, guestListColumn).setValue(event.getGuestList().map((guest) => guest.getEmail()).join(','));
        }

        if (event.getLocation() !== exisitingEvent[locationColumn - 1]) {
          hourSheet.getRange(exisitingEventRow, locationColumn).setValue(event.getLocation());
        }

        if(event.getTitle() !== exisitingEvent[titleColumn - 1]) {
          if(!isUpdateCalendarItemTitle) {
            hourSheet.getRange(exisitingEventRow, titleColumn).setValue(event.getTitle());
          }
          if(isUpdateCalendarItemTitle) {
            event.setTitle(exisitingEvent[titleColumn - 1]);
          }
        }
       
        if(event.getDescription() !== exisitingEvent[descriptionColumn - 1]) { 
          if(!isUpdateCalendarItemDescription) {
            hourSheet.getRange(exisitingEventRow, descriptionColumn).setValue(event.getDescription());
          }
          if(isUpdateCalendarItemDescription) {
            event.setDescription(exisitingEvent[descriptionColumn - 1]);
          }
        }

        return true;
      };

      // process each event for the calendar
      events.every(handleEvent);

      // remove any events in the sheet that are not in de calendar
      existingEvents.every((event, index) => {
        if (event[0] !== calendarId) {
          return true;
        };

        if (eventsLookup[event[1]]) {
          return true;
        }
        
        if (event[3] < syncStartDate) {
          return true;
        }

        hourSheet.getRange(index + 2, 1, 1, 20).clear();
        return true;
      });

      return true;
    };

    // process the calendars
    settings.calendarSettings.filter((calenderSetting) => calenderSetting.sync === true).every(processCalendar);

    formatSheet();
    SpreadsheetApp.setActiveSheet(hourSheet);

    console.log('Finished processing hours.');
  }

  const mainSpreadSheetId = par.mainSpreadsheetId;
  const mainSpreadsheet = SpreadsheetApp.openById(mainSpreadSheetId);
  const hourSheet = mainSpreadsheet.getSheetByName('Hours');
  const categoriesSheet = mainSpreadsheet.getSheetByName('Categories');
  const settings = getSettings();

  const syncStartDate = new Date();
  syncStartDate.setDate(syncStartDate.getDate() - Number(settings.syncFrom));
  
  const syncEndDate = new Date();
  syncEndDate.setDate(syncEndDate.getDate() + Number(settings.syncTo));
  
  const isUpdateCalendarItemTitle = settings.isUpdateCalendarItemTitle;
  const isUseCategoriesAsCalendarItemTitle = settings.isUseCategoriesAsCalendarItemTitle;
  const isUpdateCalendarItemDescription = settings.isUpdateCalendarItemDescription;

  const startTimeColumn = 3;
  const endTimeColumn = 4;
  const creatorsColumn = 6;
  const originalTitleColumn = 7;
  const originalDescriptionColumn = 8;
  const clientColumn = 9;
  const projectColumn = 10;
  const taskColumn = 11;
  const titleColumn = 12;
  const descriptionColumn = 13;
  const guestListColumn = 14;
  const locationColumn = 15;

  return Object.freeze({
    run: run,
  });
}
The main function used for the synchronisation
@param {Object} par The main parameter object.
@return {Object} The myTime Object.