return compute(
        key, (k, oldValue) -> (oldValue == null) ? newValue : function.apply(oldValue, newValue));
  }

  @Override
  public void putAll(Map<? extends K, ? extends V> m) {
    for (Entry<? extends K, ? extends V> e : m.entrySet()) {
      put(e.getKey(), e.getValue());
    }
  }

  @CheckForNull
  @CanIgnoreReturnValue
  @Override

    checkNotNull(value);
    int hash = hash(key);
    return segmentFor(hash).put(key, hash, value, true);
  }

  @Override
  public void putAll(Map<? extends K, ? extends V> m) {
    for (Entry<? extends K, ? extends V> e : m.entrySet()) {
      put(e.getKey(), e.getValue());
    }
  }

  @CheckForNull
  @CanIgnoreReturnValue
  @Override