Merge remote-tracking branch 'raywenderlich/master'

Author: shabirjan

Fizz Buzz/FizzBuzz.playground/Contents.swift

@@ -1,3 +1,8 @@
+// last checked with Xcode 9.0b4
+#if swift(>=4.0)
+print("Hello, Swift 4!")
+#endif
+
 func fizzBuzz(_ numberOfTurns: Int) {
   for i in 1...numberOfTurns {
     var result = ""

GCD/GCD.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
+
 // Recursive version
 func gcd(_ a: Int, _ b: Int) -> Int {
   let r = a % b

Palindromes/Palindromes.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
+
 import Foundation
 
 /**

Queue/Queue.playground/Contents.swift

@@ -1,3 +1,9 @@
+
+// last checked with Xcode 9.0b4
+#if swift(>=4.0)
+print("Hello, Swift 4!")
+#endif
+
 /*
   Queue
 

Stack/Stack.playground/Contents.swift

@@ -1,3 +1,9 @@
+
+// last checked with Xcode 9.0b4
+#if swift(>=4.0)
+print("Hello, Swift 4!")
+#endif
+
 /*
   Stack