diff --git a/src/basic/Operation.kt b/src/basic/Operation.kt
index b12704a..cdcd736 100644
--- a/src/basic/Operation.kt
+++ b/src/basic/Operation.kt
@@ -55,4 +55,11 @@ fun main(args: Array<String>) {
     println(e <= f)
     println(e == f)
     println(e.compareTo(f))
+
+    var g = true
+    var h = false
+    println(!g)
+    println(!h)
+    println(g && h)
+    println(g || h)
 }
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