import groovy.lang.Closure

fun somePlugin(action: SomePluginExtension.() -> Unit) =
    SomePluginExtension.action()

object SomePluginExtension {

    fun takingParameterLessClosure(closure: Closure<*>) =
        require(closure.call() == "result") { "parameter-less closure" }

    fun takingUnaryClosure(closure: Closure<*>) =
        require(closure.call("foo") == "result from single parameter foo") { "unary closure" }