code: final boolean applyAsDelimiter(Parser<?> parser) {
      ErrorType oldValue = overrideErrorType;
      overrideErrorType = ErrorType.DELIMITING;
      int oldStep = step;
      boolean ok = parser.apply(this);
      if (ok) step = oldStep;
      overrideErrorType = oldValue;
      return ok;
    }
docs: Runs {@code parser} with error recording suppressed.