Challenge 1: Open Class & Override — Solution

open class Employee(val name: String) {
    open fun payDescription() = "$name receives a standard salary"
}

class Manager(name: String, val bonus: Double) : Employee(name) {
    override fun payDescription() = "$name receives a standard salary plus a $bonus bonus"
}

fun main() {
    val staff: Employee = Manager("Alice", 5000.0)
    println(staff.payDescription())
}

/*
Output:
Alice receives a standard salary plus a 5000.0 bonus

Notes:
- staff is declared with the Employee type, but holds a Manager instance.
  Calling payDescription() still runs Manager's override — this is
  polymorphism: the actual object's type decides which method body runs,
  not the declared variable type.
- Employee needed "open class" and "open fun payDescription()" for this
  to compile at all; both class and method are final by default in Kotlin.
- Manager's constructor passes name straight through to Employee's
  constructor via ": Employee(name)".
*/