WeekDayCollection Class

public class WeekDayCollection : IList<WeekDay>, 
	ICollection<WeekDay>, IEnumerable<WeekDay>, IEnumerable

Public Class WeekDayCollection
	Implements IList(Of WeekDay), ICollection(Of WeekDay), 
	IEnumerable(Of WeekDay), IEnumerable

public ref class WeekDayCollection : IList<WeekDay^>, 
	ICollection<WeekDay^>, IEnumerable<WeekDay^>, IEnumerable

type WeekDayCollection =  
    class
        interface IList<WeekDay>
        interface ICollection<WeekDay>
        interface IEnumerable<WeekDay>
        interface IEnumerable
    end

var project = new Project();
var calendar = project.Calendars.GetByName("Standard");

// clear week days
calendar.WeekDays.Clear();

calendar.WeekDays.Add(WeekDay.CreateDefaultWorkingDay(DayType.Monday));
calendar.WeekDays.Add(WeekDay.CreateDefaultWorkingDay(DayType.Tuesday));
calendar.WeekDays.Add(WeekDay.CreateDefaultWorkingDay(DayType.Wednesday));
calendar.WeekDays.Add(WeekDay.CreateDefaultWorkingDay(DayType.Thursday));
calendar.WeekDays.Add(WeekDay.CreateDefaultWorkingDay(DayType.Friday));
var saturday = WeekDay.CreateDefaultWorkingDay(DayType.Saturday);
var sunday = WeekDay.CreateDefaultWorkingDay(DayType.Sunday);

calendar.WeekDays.Add(saturday);
calendar.WeekDays.Add(sunday);

var fridayWorkingTimes = new List<WorkingTime> { new WorkingTime(new DateTime(2020, 4, 13, 8, 0, 0), new DateTime(2020, 4, 13, 12, 0, 0)) };

var friday = new WeekDay(DayType.Friday, fridayWorkingTimes);
if (calendar.WeekDays.Contains(friday))
{
    calendar.WeekDays.Insert(4, friday);
}

Console.WriteLine("Calendar: " + calendar.Name);
Console.WriteLine("Week days count: " + calendar.WeekDays.Count);
foreach (var day in calendar.WeekDays)
{
    Console.WriteLine(day.DayType);
    foreach (var workingTime in day.WorkingTimes)
    {
        Console.WriteLine("From: " + workingTime.FromTime);
        Console.WriteLine("To: " + workingTime.ToTime);
        Console.WriteLine();
    }
}

// remove saturday week day
calendar.WeekDays.RemoveAt(5);

// remove sunday week day
if (calendar.WeekDays.IndexOf(saturday) > 0)
{
    calendar.WeekDays.Remove(sunday);
}

Console.WriteLine("Working times after weekend was removed: ");
List<WeekDay> weekDays = calendar.WeekDays.ToList();
foreach (var day in weekDays)
{
    Console.WriteLine(day.DayType);
    foreach (var workingTime in day.WorkingTimes)
    {
        Console.WriteLine("From: " + workingTime.FromTime);
        Console.WriteLine("To: " + workingTime.ToTime);
        Console.WriteLine();
    }
}

var hour24Calendar = project.Calendars.Add("24 Hours");
Calendar.Make24HourCalendar(hour24Calendar);

// copy week days
var weekDaysArray = new WeekDay[calendar.WeekDays.Count];
calendar.WeekDays.CopyTo(weekDaysArray, 0);

foreach (var weekDay in weekDaysArray)
{
    hour24Calendar.WeekDays.Add(weekDay);
}