code: @Cached
      @DontLabel
      public Rule charRange(final char cLow, final char cHigh)
      {
          return cLow == cHigh ? ch(cLow) : new CharRangeMatcher(cLow, cHigh);
      }
docs: Match an inclusive range of {@code char}s
  
  @param cLow the start char of the range (inclusively)
  @param cHigh the end char of the range (inclusively)
  @return a rule