function loadActivitySchedule_(ss) {
  let timeZone = ss.getSpreadsheetTimeZone();
  let sheet = ss.getSheetByName('Activity Schedule');
  let rows = sheet.getSheetValues(
      sheet.getFrozenRows() + 1, 1,
      sheet.getLastRow() - 1, sheet.getLastRow());
  let activities = rows.map(function(row, index) {
    let name = row[0];
    let startAt = new Date(row[1]);
    let endAt = new Date(row[2]);
    let capacity = parseInt(row[3]);
    let formattedStartAt= Utilities.formatDate(startAt, timeZone, 'EEE hh:mm a');
    let formattedEndAt = Utilities.formatDate(endAt, timeZone, 'hh:mm a');
    let description = Utilities.formatString('%s (%s-%s)', name, formattedStartAt, formattedEndAt);
    return {
      id: index,
      name: name,
      description: description,
      capacity: capacity,
      startAt: startAt,
      endAt: endAt,
      roster: [],
    };
  });
  return activities;
}
Loads the activity schedule.

@param {Spreadsheet} ss - Spreadsheet to load from
@return {object[]} Array of available activities.