[Swift 4.2] Updated Linear Search

The code worked fine in Xcode 10. I removed code snippet at the top of playground file.

Author: heyrahulrs

Linear Search/LinearSearch.playground/Contents.swift

@@ -1,10 +1,5 @@
 //: Playground - noun: a place where people can play
 
-// last checked with Xcode 9.0b4
-#if swift(>=4.0)
-print("Hello, Swift 4!")
-#endif
-
 func linearSearch<T: Equatable>(_ array: [T], _ object: T) -> Int? {
     for (index, obj) in array.enumerated() where obj == object {
         return index