docs: public final long getPackedLong(final int pos) {
          final int lead = getUint8(pos);
          if (lead < 251) return lead;
  
          switch (lead) {
              case 251:
                  return NULL_LENGTH;
              case 252:
                  return getUint16(pos + 1);
              case 253:
                  return getUint24(pos + 1);
              default: /* Must be 254 when here */
                  return getUint32(pos + 1);
          }
      }