Update Sorted Set to Swift 4.2

Author: pchelnikov

Sorted Set/SortedSet.playground/Pages/Example 1.xcplaygroundpage/Contents.swift

@@ -1,8 +1,3 @@
-// last checked with Xcode 9.0b4
-#if swift(>=4.0)
-print("Hello, Swift 4!")
-#endif
-
 //: # Example 1 with type Int
 
 var mySet = SortedSet<Int>()

Sorted Set/SortedSet.playground/Pages/Example 1.xcplaygroundpage/timeline.xctimeline

@@ -3,17 +3,17 @@
    version = "3.0">
    <TimelineItems>
       <LoggerValueHistoryTimelineItem
-         documentLocation = "file:///Users/kaichen/src/swift-algorithm-club/Sorted%20Set/SortedSet.playground/Pages/Example%201.xcplaygroundpage#CharacterRangeLen=21&amp;CharacterRangeLoc=370&amp;EndingColumnNumber=0&amp;EndingLineNumber=24&amp;StartingColumnNumber=1&amp;StartingLineNumber=23&amp;Timestamp=532757103.131521"
+         documentLocation = "file:///Users/michaelmix/git-repos/hacktoberfest-2018/swift-algorithm-club/Sorted%20Set/SortedSet.playground/Pages/Example%201.xcplaygroundpage#CharacterRangeLen=21&amp;CharacterRangeLoc=287&amp;EndingColumnNumber=0&amp;EndingLineNumber=19&amp;StartingColumnNumber=1&amp;StartingLineNumber=18&amp;Timestamp=561504226.71819"
          selectedRepresentationIndex = "0"
          shouldTrackSuperviewWidth = "NO">
       </LoggerValueHistoryTimelineItem>
       <LoggerValueHistoryTimelineItem
-         documentLocation = "file:///Users/kaichen/src/swift-algorithm-club/Sorted%20Set/SortedSet.playground/Pages/Example%201.xcplaygroundpage#CharacterRangeLen=24&amp;CharacterRangeLoc=411&amp;EndingColumnNumber=0&amp;EndingLineNumber=26&amp;StartingColumnNumber=3&amp;StartingLineNumber=25&amp;Timestamp=532757103.131695"
+         documentLocation = "file:///Users/michaelmix/git-repos/hacktoberfest-2018/swift-algorithm-club/Sorted%20Set/SortedSet.playground/Pages/Example%201.xcplaygroundpage#CharacterRangeLen=24&amp;CharacterRangeLoc=328&amp;EndingColumnNumber=0&amp;EndingLineNumber=21&amp;StartingColumnNumber=3&amp;StartingLineNumber=20&amp;Timestamp=561504226.718327"
          selectedRepresentationIndex = "0"
          shouldTrackSuperviewWidth = "NO">
       </LoggerValueHistoryTimelineItem>
       <LoggerValueHistoryTimelineItem
-         documentLocation = "file:///Users/kaichen/src/swift-algorithm-club/Sorted%20Set/SortedSet.playground/Pages/Example%201.xcplaygroundpage#CharacterRangeLen=25&amp;CharacterRangeLoc=510&amp;EndingColumnNumber=0&amp;EndingLineNumber=32&amp;StartingColumnNumber=3&amp;StartingLineNumber=31&amp;Timestamp=532757103.131826"
+         documentLocation = "file:///Users/michaelmix/git-repos/hacktoberfest-2018/swift-algorithm-club/Sorted%20Set/SortedSet.playground/Pages/Example%201.xcplaygroundpage#CharacterRangeLen=25&amp;CharacterRangeLoc=427&amp;EndingColumnNumber=0&amp;EndingLineNumber=27&amp;StartingColumnNumber=3&amp;StartingLineNumber=26&amp;Timestamp=561504226.718428"
          selectedRepresentationIndex = "0"
          shouldTrackSuperviewWidth = "NO">
       </LoggerValueHistoryTimelineItem>