double z = a.getAndUpdate(value -> value + y);
        assertBitEquals(x, z);
        assertBitEquals(x + y, a.get());
      }
    }
  }

  /**
   * getAndUpdate with subtract stores subtraction of value from current, and returns previous value
   */
  public void testGetAndUpdateWithSubtract() {
    for (double x : VALUES) {
      for (double y : VALUES) {

  }

  public void testIsPowerOfTwo() {
    for (BigInteger x : ALL_BIGINTEGER_CANDIDATES) {
      // Checks for a single bit set.
      boolean expected = x.signum() > 0 & x.and(x.subtract(ONE)).equals(ZERO);
      assertEquals(expected, BigIntegerMath.isPowerOfTwo(x));
    }
  }

  public void testLog2ZeroAlwaysThrows() {
    for (RoundingMode mode : ALL_ROUNDING_MODES) {

    checkBigIntegerConversion(
        "::ffff:ffff:ffff:ffff", BigInteger.ONE.shiftLeft(64).subtract(BigInteger.ONE));
    checkBigIntegerConversion(
        "ffff:ffff:ffff:ffff:ffff:ffff:ffff:ffff",
        BigInteger.ONE.shiftLeft(128).subtract(BigInteger.ONE));
  }

  public void testFromIpv4BigIntegerInputTooLarge() {
    IllegalArgumentException expected =
        assertThrows(

        } else if (nanos <= 0) {
          return false;
        } else {
          long now = System.nanoTime();
          NANOSECONDS.timedWait(lock, nanos);
          nanos -= System.nanoTime() - now; // subtract the actual time we waited
        }
      }
    }
  }

  /**
   * Checks if the executor has been shut down and increments the running task count.
   *

            if (cal.hasClass('left')) {
                this.leftCalendar.month.subtract(1, 'month');
                if (this.linkedCalendars)
                    this.rightCalendar.month.subtract(1, 'month');
            } else {
                this.rightCalendar.month.subtract(1, 'month');
            }
            this.updateCalendars();
        },

    value: T?,
  ): Tags {
    // Create a copy of this `LinkedTags` that doesn't have a mapping for `key`.
    val thisMinusKey =
      when {
        key == this.key -> {
          next
        }

        // Subtract this!

        else -> {
          val nextMinusKey = next.plus(key, null)
          when {
            nextMinusKey === next -> this

            // Same as the following line, but with fewer allocations.

    requireLinks()[i] = value;
  }

  /*
   * We don't define getPredecessor+getSuccessor and setPredecessor+setSuccessor here because
   * they're defined above -- including logic to add and subtract 1 to map between the values stored
   * in the predecessor/successor arrays and the indexes in the elements array that they identify.
   */

  }

  @AndroidIncompatible // slow
  public void testLessThanBranchFree() {
    for (long x : ALL_LONG_CANDIDATES) {
      for (long y : ALL_LONG_CANDIDATES) {
        BigInteger difference = BigInteger.valueOf(x).subtract(BigInteger.valueOf(y));
        if (fitsInLong(difference)) {
          int expected = (x < y) ? 1 : 0;
          int actual = LongMath.lessThanBranchFree(x, y);
          assertEquals(expected, actual);
        }

        UnsignedInteger aUnsigned = UnsignedInteger.fromIntBits(a);
        UnsignedInteger bUnsigned = UnsignedInteger.fromIntBits(b);
        int expected =
            force32(aUnsigned.bigIntegerValue().subtract(bUnsigned.bigIntegerValue()).intValue());
        UnsignedInteger unsignedSub = aUnsigned.minus(bUnsigned);
        assertThat(unsignedSub.intValue()).isEqualTo(expected);
      }
    }
  }

  }

  @AndroidIncompatible // slow
  public void testCheckedSubtract() {
    for (int a : ALL_INTEGER_CANDIDATES) {
      for (int b : ALL_INTEGER_CANDIDATES) {
        BigInteger expectedResult = valueOf(a).subtract(valueOf(b));
        boolean expectedSuccess = fitsInInt(expectedResult);
        try {
          assertEquals(a - b, IntMath.checkedSubtract(a, b));
          assertTrue(expectedSuccess);