docs: static long biggestPowerTen(int number,
                                  int number_bits) {
          int power, exponent;
          switch (number_bits) {
              case 32:
              case 31:
              case 30:
                  if (kTen9 <= number) {
                      power = kTen9;
                      exponent = 9;
                      break;
                  }  // else fallthrough
              case 29:
              case 28:
              case 27:
                  if (kTen8 <= number) {
                      power = kTen8;
                      exponent = 8;
                      break;
                  }  // else fallthrough
              case 26:
              case 25:
              case 24:
                  if (kTen7 <= number) {
                      power = kTen7;
                      exponent = 7;
                      break;
                  }  // else fallthrough
              case 23:
              case 22:
              case 21:
              case 20:
                  if (kTen6 <= number) {
                      power = kTen6;
                      exponent = 6;
                      break;
                  }  // else fallthrough
              case 19:
              case 18:
              case 17:
                  if (kTen5 <= number) {
                      power = kTen5;
                      exponent = 5;
                      break;
                  }  // else fallthrough
              case 16:
              case 15:
              case 14:
                  if (kTen4 <= number) {
                      power = kTen4;
                      exponent = 4;
                      break;
                  }  // else fallthrough
              case 13:
              case 12:
              case 11:
              case 10:
                  if (1000 <= number) {
                      power = 1000;
                      exponent = 3;
                      break;
                  }  // else fallthrough
              case 9:
              case 8:
              case 7:
                  if (100 <= number) {
                      power = 100;
                      exponent = 2;
                      break;
                  }  // else fallthrough
              case 6:
              case 5:
              case 4:
                  if (10 <= number) {
                      power = 10;
                      exponent = 1;
                      break;
                  }  // else fallthrough
              case 3:
              case 2:
              case 1:
                  if (1 <= number) {
                      power = 1;
                      exponent = 0;
                      break;
                  }  // else fallthrough
              case 0:
                  power = 0;
                  exponent = -1;
                  break;
              default:
                  // Following assignments are here to silence compiler warnings.
                  power = 0;
                  exponent = 0;
                  // UNREACHABLE();
          }
          return ((long)power << 32) | (0xffffffffL & exponent);
      }