%YAML 1.1
---
!!map {
  ? !!str "explicit key1"
  : !!str "explicit value",
  ? !!str "explicit key2"
  : !!null "",
  ? !!str "explicit key3"
  : !!null "",
  ? !!str "simple key1"
  : !!str "explicit value",
  ? !!str "simple key2"
  : !!null "",
  ? !!str "simple key3"
  : !!null "",
}