Visitor Design Pattern

A.Visitor.Design.Pattern.cs

namespace Visitor
{
    class Program
    {
        /*
         * The Visitor pattern allows you to define new operations on a type without changing the type itself.
         */
        static void Main(string[] args)
        {
            var employee = new Employee
            {
                Name = "Ahmed",
                Salary = 10000,
                DaysTakenOff = 0
            };

            employee.TakeVacation(14);

            Console.WriteLine(employee.Salary);

            var vacationVisitor = new VacationCalculator();

            /*
             * Here we defined a new operation on the IVisitable 'Employee' type by the IVisitor 'VacationCalculator' type without
             * modifying the 'Employee' type,
             */
             
            employee.Accept(vacationVisitor);

            Console.WriteLine(employee.Salary);

            Console.ReadLine();
        }
    }
}

B.IVisitable.cs

namespace Visitor
{
    public interface IVisitable
    {
        /*
         * Types that require new operations without modification should implement the IVisitable interface to accept incoming 
         * IVisitor(s) that will perform these operations
         */
        void Accept(IVisitor visitor);
    }
}

C.Employee.cs

namespace Visitor
{
    public class Employee : IVisitable
    {
        public string Name { get; set; }

        public double Salary { get; set; }

        public int DaysTakenOff { get; set; }

        public void Accept(IVisitor visitor) //The IVisitor's Visit method is called with relevant parameters
        {
            visitor.Visit(this);
        }

        public override string ToString()
        {
                return $"Employee Name: {Name}, Salary: {Salary}, has taken {DaysTakenOff} days off this year.";
        }

        public void TakeVacation(int vacationDays) => DaysTakenOff += vacationDays;
	}
}

D.IVisitor.cs

namespace Visitor
{
    public interface IVisitor
    {
        void Visit(IVisitable visitable, params object[] arg);
    }
}

E.VacationCalculator.cs

namespace Visitor
{
    public class VacationCalculator : IVisitor
    {
        const int MaximumVacationDaysPerYear = 10;

        public void Visit(IVisitable visitable, params object[] arg)
        {
            if (visitable is Employee employee)
            {
                var daysTakenOff = employee.DaysTakenOff;
                var employeeSalary = employee.Salary;

                if (daysTakenOff > MaximumVacationDaysPerYear)
                {
                    employee.Salary -= (employeeSalary * (((double)daysTakenOff - MaximumVacationDaysPerYear) / 365));
                }
            }
        }
    }
}