Public Interface IEmployeeManager
    ''' <summary>
    ''' A collection of all the employees.
    ''' </summary>
    ''' <returns></returns>
    ReadOnly Property Employees As ICollection(Of IEmployee)

    ''' <summary>
    ''' All the non-selected employees.
    ''' </summary>
    ''' <returns></returns>
    ReadOnly Property AvailableEmployees As ICollection(Of IEmployee)

    ''' <summary>
    ''' The selected employees.
    ''' </summary>
    ''' <returns></returns>
    ReadOnly Property SelectedEmployees As ICollection(Of IEmployee)

    ''' <summary>
    ''' Get a selected employee corresponding to an employee number. This is merely the pre-defined index for each possible employee.
    ''' If no employee was selected, 'Nothing' will be returned.
    ''' </summary>
    ''' <param name="employeeNumber">The number (index) of the employee, 0 based</param>
    ''' <returns>The employee</returns>
    Function GetSelectedEmployee(employeeNumber As Integer) As IEmployee

    ''' <summary>
    ''' Select and store the chosen employee.
    ''' </summary>
    ''' <param name="employeeNumber">The number (index) for the employee</param>
    ''' <param name="employee"></param>
    Sub SelectEmployee(employeeNumber As Integer, employee As IEmployee)

    ''' <summary>
    ''' Deselect an employee.
    ''' </summary>
    ''' <param name="employeeNumber">The number (index) of an employee, 0 based</param>
    Sub RemoveEmployeeSelection(employeeNumber As Integer)
End Interface