Extract Function: Implement duplicate search

idea/testData/refactoring/extractFunction/duplicates/outputValueAndUnitMatching.kt

@@ -0,0 +1,22 @@
+// WITH_RUNTIME
+// PARAM_TYPES: kotlin.Int
+// PARAM_DESCRIPTOR: val z: kotlin.Int defined in test
+
+// SIBLING:
+fun test(): () -> Int {
+    val z = 1
+    return {
+        <selection>println(z)
+        z + 1</selection>
+    }
+}
+
+fun foo1(a: Int): Int {
+    val t = println(a)
+    return a + 1
+}
+
+fun foo2(a: Int) {
+    println(a)
+    a + 1
+}