   ///  - Returns: *true* if contains match, otherwise false.
   public func contains(_ string: String, caseSensitive: Bool) -> Bool {
     if (caseSensitive) {
-      return self.contains(string)
+      return contains(string)
     } else {
-      return (self.range(of: string, options: .caseInsensitive) != nil)
+      return range(of: string, options: .caseInsensitive) != nil
     }
   }
 

  ///
  ///  - parameter prefix: prefix to be removed.
  public func removingSuffix(_ suffix: String) -> String {
    guard self.hasSuffix(suffix) else { return self }
    return self.removingSuffix(fromPosition: suffix.length)
  }

  /// **Mechanica**

  public func replacingCharacters(in range: CountableRange<Int>, with replacement: String) -> String {
    let start = index(startIndex, offsetBy: range.lowerBound)
    let end   = index(start, offsetBy: range.count)
    return replacingCharacters(in: start ..< end, with: replacement)
  }

  /// **Mechanica**
