[Swift 4] Update Binary Search Tree

Author: remlostime

Diff for: Binary Search Tree/Solution 1/BinarySearchTree.playground/Contents.swift

@@ -1,5 +1,10 @@
 //: Playground - noun: a place where people can play
 
+// last checked with Xcode 9.0b4
+#if swift(>=4.0)
+print("Hello, Swift 4!")
+#endif
+
 let tree = BinarySearchTree<Int>(value: 7)
 tree.insert(value: 2)
 tree.insert(value: 5)

Diff for: Binary Search Tree/Solution 1/BinarySearchTree.playground/timeline.xctimeline

@@ -1,5 +1,10 @@
 //: Playground - noun: a place where people can play
 
+// last checked with Xcode 9.0b4
+#if swift(>=4.0)
+print("Hello, Swift 4!")
+#endif
+
 // Each time you insert something, you get back a completely new tree.
 var tree = BinarySearchTree.leaf(7)
 tree = tree.insert(newValue: 2)