PlaceholderAPI usage

papi {
    expansion("placeholder") {
        then("asdf") {
            requires { player != null }
            executes {
                "fdsa"
            }
        }
        argument("value") {
            executes {
                val value: String by arguments
                value
            }
            argument("value2") {
                executes {
                    val value: String by arguments
                    val value2: String by arguments
                    value + value2
                }
            }
        }
    }
}
ppapi("%placeholder_asdf%")

It looks like kommand code.
also it doesn't throw exception when PlaceholderAPI doesn't exist