Challenge 2: Elvis Operator Defaults — Solution

fun displayName(nickname: String?): String = nickname ?: "Anonymous"

fun main() {
    println(displayName(null))
    println(displayName("Phil"))
}

/*
Output:
Anonymous
Phil

Notes:
- displayName is written as a single-expression function; the entire body
  is the Elvis expression "nickname ?: \"Anonymous\"".
- When nickname is null, the left side of ?: is null, so the expression
  evaluates to the right side, "Anonymous".
- When nickname is "Phil" (non-null), the left side is used as-is and the
  right side is never evaluated.
*/