code: function getStartDate(date, minDate, maxDate) {
    let startDate = startOfDay(date);
    if (minDate) {
      const minDateNormalized = startOfDay(minDate);
      if (isBefore(startDate, minDateNormalized)) {
        startDate = minDateNormalized;
      }
    }
    if (maxDate) {
      const maxDateNormalized = startOfDay(maxDate);
      if (isBefore(maxDateNormalized, startDate)) {
        startDate = maxDateNormalized;
      }
    }
    return startDate;
  }
docs: Figures out the actual start date based on
  the min and max dates available.
  @param {Date} date The we want to start the calendar at
  @param {Date} minDate The earliest date available to start at
  @param {Date} maxDate The latest date available to start at
  @returns {Date} The actual start date