Set<K> ks = keySet;
    return (ks != null) ? ks : (keySet = new KeySet(this));
  }

  Collection<V> values;

  @Override
  public Collection<V> values() {
    // does not impact recency ordering
    Collection<V> vs = values;
    return (vs != null) ? vs : (values = new Values(this));
  }

  Set<Entry<K, V>> entrySet;

  @Override
  public Set<Entry<K, V>> entrySet() {

     * Creates a {@link StreamOf} instance from the provided values.
     * If the input array is {@code null}, an empty stream is returned.
     *
     * @param <T> The type of elements in the stream.
     * @param values The elements to be included in the stream. Can be {@code null}.
     * @return A {@link StreamOf} instance containing the provided values, or an empty stream if {@code values} is {@code null}.
     */
    @SafeVarargs

 *
 * @since 4.0.0
 */
@Experimental
public interface Interpolator extends Service {

    /**
     * Interpolates the values in the given map using the provided callback function.
     * This method defaults to setting empty strings for unresolved placeholders.
     *
     * @param properties The map containing key-value pairs to be interpolated.

    if is_sequence_field(field) and isinstance(values, (ImmutableMultiDict, Headers)):
        value = values.getlist(alias)
    else:
        value = values.get(alias, None)
    if (
        value is None
        or (
            isinstance(field.field_info, params.Form)
            and isinstance(value, str)  # For type checks
            and value == ""
        )

	return newCfgKVS
}

// Set sets a value, if not sets a default value.
func (kvs *KVS) Set(key, value string) {
	for i, kv := range *kvs {
		if kv.Key == key {
			(*kvs)[i] = KV{
				Key:   key,
				Value: value,
			}
			return
		}
	}
	*kvs = append(*kvs, KV{
		Key:   key,
		Value: value,
	})
}

// Get - returns the value of a key, if not found returns empty.

      newerThan: "7d10h31s" # match objects newer than this value (e.g. 7d10h31s)
      olderThan: "7d" # match objects older than this value (e.g. 7d10h31s)
#      createdAfter: "date" # match objects created after "date"
#      createdBefore: "date" # match objects created before "date"

      ## NOTE: tags are not supported when "source" is remote.
      tags:
         - key: "name"

   * Object[])} comparator when comparing a value outside the set of values it can compare.
   * Extending {@link ClassCastException} may seem odd, but it is required.
   */
  static final class IncomparableValueException extends ClassCastException {
    final Object value;

    IncomparableValueException(Object value) {
      super("Cannot compare value: " + value);
      this.value = value;
    }

	// Adding a nil value
	lc.Add("key1", nil)

	value, exists := lc.Get("key1")
	if value != nil || !exists {
		t.Fatalf("unexpected value or existence flag for key1: value=%v, exists=%v", value, exists)
	}

	// Adding an entry with the same key but different value
	newVal := "val1"
	lc.Add("key1", &newVal)

	value, exists = lc.Get("key1")
	if value != &newVal || !exists {

	// ErrInvalidDB invalid db
	ErrInvalidDB = errors.New("invalid db")
	// ErrInvalidValue invalid value
	ErrInvalidValue = errors.New("invalid value, should be pointer to struct or slice")
	// ErrInvalidValueOfLength invalid values do not match length
	ErrInvalidValueOfLength = errors.New("invalid association values, length doesn't match")
	// ErrPreloadNotAllowed preload is not allowed when count is used

      extends SimpleImmutableEntry<Range<K>, V> {
    RangeMapEntry(Cut<K> lowerBound, Cut<K> upperBound, V value) {
      this(Range.create(lowerBound, upperBound), value);
    }

    RangeMapEntry(Range<K> range, V value) {
      super(range, value);
    }

    boolean contains(K value) {
      return getKey().contains(value);
    }

    Cut<K> getLowerBound() {
      return getKey().lowerBound;
    }