code: private DateTimeFormatterBuilder appendValue(NumberPrinterParser pp) {
          if (active.valueParserIndex >= 0 &&
                  active.printerParsers.get(active.valueParserIndex) instanceof NumberPrinterParser) {
              final int activeValueParser = active.valueParserIndex;
  
              // adjacent parsing mode, update setting in previous parsers
              NumberPrinterParser basePP = (NumberPrinterParser) active.printerParsers.get(activeValueParser);
              if (pp.minWidth == pp.maxWidth && pp.signStyle == SignStyle.NOT_NEGATIVE) {
                  // Append the width to the subsequentWidth of the active parser
                  basePP = basePP.withSubsequentWidth(pp.maxWidth);
                  // Append the new parser as a fixed width
                  appendInternal(pp.withFixedWidth());
                  // Retain the previous active parser
                  active.valueParserIndex = activeValueParser;
              } else {
                  // Modify the active parser to be fixed width
                  basePP = basePP.withFixedWidth();
                  // The new parser becomes the mew active parser
                  active.valueParserIndex = appendInternal(pp);
              }
              // Replace the modified parser with the updated one
              active.printerParsers.set(activeValueParser, basePP);
          } else {
              // The new Parser becomes the active parser
              active.valueParserIndex = appendInternal(pp);
          }
          return this;
      }
docs: Appends a fixed width printer-parser.
  
  @param width  the width
  @param pp  the printer-parser, not null
  @return this, for chaining, not null