public void testPutAfterHash() {
    Hasher hasher = Hashing.hmacMd5(MD5_KEY).newHasher();

    assertEquals(
        "9753980fe94daa8ecaa82216519393a9",
        hasher.putString("The quick brown fox jumps over the lazy dog", UTF_8).hash().toString());
    assertThrows(IllegalStateException.class, () -> hasher.putInt(42));
  }

  public void testHashTwice() {
    Hasher hasher = Hashing.hmacMd5(MD5_KEY).newHasher();

  public void testPutAfterHash() {
    Hasher hasher = Hashing.hmacMd5(MD5_KEY).newHasher();

    assertEquals(
        "9753980fe94daa8ecaa82216519393a9",
        hasher.putString("The quick brown fox jumps over the lazy dog", UTF_8).hash().toString());
    assertThrows(IllegalStateException.class, () -> hasher.putInt(42));
  }

  public void testHashTwice() {
    Hasher hasher = Hashing.hmacMd5(MD5_KEY).newHasher();

	borrowed []hash.Hash
}

// Borrow a single hasher.
func (h *HashBorrower) Borrow() hash.Hash {
	hasher := h.pool.Get().(hash.Hash)
	h.borrowed = append(h.borrowed, hasher)
	hasher.Reset()
	return hasher
}

// ReturnAll will return all borrowed hashes.
func (h *HashBorrower) ReturnAll() {
	for _, hasher := range h.borrowed {
		h.pool.Put(hasher)
	}
	h.borrowed = nil
}

    @CanIgnoreReturnValue
    @Override
    public Hasher putInt(int i) {
      update(4, i);
      return this;
    }

    @CanIgnoreReturnValue
    @Override
    public Hasher putLong(long l) {
      update(4, (int) l);
      update(4, l >>> 32);
      return this;
    }

    @CanIgnoreReturnValue
    @Override
    public Hasher putChar(char c) {
      update(2, c);
      return this;

}

// Matches returns whether given content matches c.
func (c Checksum) Matches(content []byte) error {
	if len(c.Encoded) == 0 {
		return nil
	}
	hasher := c.Type.Hasher()
	_, err := hasher.Write(content)
	if err != nil {
		return err
	}
	sum := hasher.Sum(nil)
	if !bytes.Equal(sum, c.Raw) {
		return ChecksumMismatch{
			Want: c.Encoded,
			Got:  base64.StdEncoding.EncodeToString(sum),
		}
	}

  }

  public void testHashIntVsForLoop() {
    int input = 42;
    HashCode expected = Hashing.md5().hashInt(input);

    Hasher hasher = Hashing.md5().newHasher();
    for (int i = 0; i < 32; i += 8) {
      hasher.putByte((byte) (input >> i));
    }
    HashCode actual = hasher.hash();

    assertEquals(expected, actual);
  }

  private static final String EMPTY_STRING = "";

 *
 * <p>The primary way to provide the data that your hash function should act on is via a {@link
 * Hasher}. Obtain a new hasher from the hash function using {@link #newHasher}, "push" the relevant
 * data into it using methods like {@link Hasher#putBytes(byte[])}, and finally ask for the {@code
 * HashCode} when finished using {@link Hasher#hash}. (See an {@linkplain #newHasher example} of
 * this.)
 *

  }

  static HashCode randomHash(HashFunction hashFunction, Random random, int numActions) {
    Hasher hasher = hashFunction.newHasher();
    for (int i = 0; i < numActions; i++) {
      RandomHasherAction.pickAtRandom(random).performAction(random, ImmutableSet.of(hasher));
    }
    return hasher.hash();
  }

  private static void assertShortcutsAreEquivalent(HashFunction hashFunction, int trials) {

  }

  static HashCode randomHash(HashFunction hashFunction, Random random, int numActions) {
    Hasher hasher = hashFunction.newHasher();
    for (int i = 0; i < numActions; i++) {
      RandomHasherAction.pickAtRandom(random).performAction(random, ImmutableSet.of(hasher));
    }
    return hasher.hash();
  }

  private static void assertShortcutsAreEquivalent(HashFunction hashFunction, int trials) {

  }

  public void testHashIntVsForLoop() {
    int input = 42;
    HashCode expected = Hashing.md5().hashInt(input);

    Hasher hasher = Hashing.md5().newHasher();
    for (int i = 0; i < 32; i += 8) {
      hasher.putByte((byte) (input >> i));
    }
    HashCode actual = hasher.hash();

    assertEquals(expected, actual);
  }

  private static final String EMPTY_STRING = "";