code:

// yay an interface
interface Yospos {
  fun bithc(): String
  val lol: String
}

// here's a concrete implementation
class YosposBithc : Yospos {
  override fun bithc() = "your os is a pos"
  override val lol = "lol, just lol"
}

// here's our wrapper that uses a delegate thing
// the constructor takes a parameter "item"
// the YosposWrapper implements Yospos, which is delegated BY "item"
class YosposWrapper(item: Yospos) : Yospos by item {
  // lets ONLY override bithc(), let it delegate everything else to the wrapped item
  override fun bithc() = "well how about that"
}

fun main(args: Array<String>) {
  val og: Yospos = YosposBithc()
  val wrapped: Yospos = YosposWrapper(i)
  println("original: ${og.bithc()}, ${og.lol}")
  println("wrapped: ${wrapped.bithc()}, ${wrapped.lol}")
}

// this outputs:
// "original: your os is a pos, lol, just lol"
// "wrapped: well how about that, lol, just lol"