SpekImpl.kt

public fun given(description : String, givenExpression: Given.() -> Unit) {
  // code omitted
}

public class Given {
    public fun on(description: String, onExpression: On.() -> Unit) {
        // code omitted
    }
}

public class On {
    public fun it(description: String, itExpression: It.()->Unit) {
      // code omitted
    }
}

public class It {

    fun shouldEqual<T>(expected: T, actual: T) {
        assertEquals(expected, actual)
    }

    // rest of code omitted...
}