text: public override CharsRef Subtract(CharsRef output, CharsRef inc){Debug.Assert(output != null);Debug.Assert(inc != null);if (inc == NO_OUTPUT){return output;}else if (inc.Length == output.Length){return NO_OUTPUT;}else{Debug.Assert(inc.Length < output.Length, "inc.Length=" + inc.Length + " vs output.Length=" + output.Length);Debug.Assert(inc.Length > 0);return new CharsRef(output.Chars, output.Offset + inc.Length, output.Length - inc.Length);}}