average-each-group.kt

// prepare variable employees which is a list of Employee object
// Same as Task 0
employees.groupBy { it.department }
    .map { group ->
        val departmentName = group.key
        val departmentEmployees = group.value
        val departmentAverageSalary = departmentEmployees.sumBy { it.salary } / departmentEmployees.size
        println("Average salary for department $departmentName is $departmentAverageSalary")
    }