String
extension String: Mockup- 
                  
                  DeclarationSwift public static func random() -> String
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                  Generates random string of required length from supplied characters. DeclarationSwift public static func random( length: Int, characters: [Character] ) -> StringParameterslengthLength of the generated string in characters. charactersArray of characters used to generate the random string. 
 String Extension Reference
        String Extension Reference