data class FooBar(
    val a: String = ""
    val b: String = ""
    val c: Boolean = false,
    val d: Boolean = false,
    val e: String = ""
) {
    class Builder {
        private var bA: String = ""; fun a(block: () -> String) { bA = block() }
        private var bB: String = ""; fun b(block: () -> String) { bB = block() }
        private var bC: String = ""; fun c(block: () -> String) { bC = block() }
        private var bD: String = ""; fun d(block: () -> String) { bD = block() }
        private var bE: String = ""; fun e(block: () -> String) { bE = block() }
        fun build(): FooBar = FooBar(bA, bB, bC, bD, bE)
    }
    companion object {
        inline fun builder(block: Builder.() -> Unit): FooBar = Builder().apply(block).build()
    }
}