if (predecessors != null) {
      checkState(predecessors.remove(node));
    }
    return node;
  }

  @Override
  public N removeOutEdge(E edge) {
    N node = super.removeOutEdge(edge);
    Multiset<N> successors = getReference(successorsReference);
    if (successors != null) {
      checkState(successors.remove(node));
    }
    return node;
  }

  @Override

 * from the {@code pathScope} and the injected field type. If the type
 * is {@link org.apache.maven.api.Node Node} and {@code pathScope == ""},
 * then the dependencies will be <i>collected</i>.
 * If the type is {@link org.apache.maven.api.Node Node} or
 * {@code List<}{@link org.apache.maven.api.Node Node}{@code >},
 * and {@code pathScope != ""}, the dependencies will be <i>flattened</i>.

 * transformation:
 *
 * {@snippet :
 * someGraphAlgorithm(startNode, node -> ImmutableList.of(node.mother(), node.father()));
 * }
 *
 * <p>Graph algorithms that need additional capabilities (accessing both predecessors and
 * successors, iterating over the edges, etc.) should declare their input to be of a type that
 * provides those capabilities, such as {@link Graph}, {@link ValueGraph}, or {@link Network}.
 *

    * `dict`의 값(value)는 `float`타입이다. (각 아이템의 가격(price))

#### `Optional`

`str`과 같이 타입을 선언할 때 `Optional`을 쓸 수도 있는데, "선택적(Optional)"이기때문에 `None`도 될 수 있습니다:

```Python hl_lines="1  4"
{!../../docs_src/python_types/tutorial009.py!}
```

`Optional[str]`을 `str` 대신 쓰게 되면, 특정 값이 실제로는 `None`이 될 수도 있는데 항상 `str`이라고 가정하는 상황에서 에디터가 에러를 찾게 도와줄 수 있습니다.

#### Generic(제네릭) 타입

이 타입은 대괄호 안에 매개변수를 가지며, 종류는:

* `List`

  float: none;
}

.daterangepicker.single .drp-selected {
  display: none;
}

.daterangepicker.show-calendar .drp-calendar {
  display: block;
}

.daterangepicker.show-calendar .drp-buttons {
  display: block;
}

.daterangepicker.auto-apply .drp-buttons {
  display: none;
}

.daterangepicker .drp-calendar {
  display: none;

  @Override
  public Set<N> adjacentNodes(N node) {
    return delegate().adjacentNodes(node);
  }

  @Override
  public Set<N> predecessors(N node) {
    return delegate().predecessors(node);
  }

  @Override
  public Set<N> successors(N node) {
    return delegate().successors(node);
  }

  @Override
  public int degree(N node) {
    return delegate().degree(node);
  }

  @Override

  @CanIgnoreReturnValue
  N removeOutEdge(E edge);

  /**
   * Add {@code edge} to the set of incoming edges. Implicitly adds {@code node} as a predecessor.
   */
  void addInEdge(E edge, N node, boolean isSelfLoop);

  /** Add {@code edge} to the set of outgoing edges. Implicitly adds {@code node} as a successor. */
  void addOutEdge(E edge, N node);

     *         specified dependency node's children and proceed to its next sibling
     */
    boolean enter(@Nonnull Node node);

    /**
     * Ends the visit to the specified dependency node.
     *
     * @param node the dependency node to visit
     * @return <code>true</code> to visit the specified dependency node's next sibling, <code>false</code> to skip the
     *         specified dependency node's next siblings and proceed to its parent

     * @return the parsed XML node
     * @throws XMLStreamException if there is an error parsing the XML
     */
    protected abstract XmlNode doRead(XMLStreamReader reader, InputLocationBuilder locationBuilder)
            throws XMLStreamException;

    /**
     * Implementation method for writing an XML node to a writer.
     *
     * @param node the XML node to write
     * @param writer the writer to write to

                log.info("Failed to send node status request for " + addr, ioe);
                throw new UnknownHostException(addr.toString());
            }
            if (response.received && response.resultCode == 0) {

                /*
                 * For name queries resolved by different sources (e.g. WINS,
                 * BCAST, Node Status) we need to augment the hashcode generated