---

回到之前的代码示例，**FastAPI** 将会：

* 校验 `GET` 和 `PUT` 请求的路径中是否包含 `item_id`。
* 校验 `GET` 和 `PUT` 请求中的 `item_id` 是否为 `int` 类型。
    * 如果不是，客户端会看到清晰有用的错误信息。
* 对于 `GET` 请求，检查是否存在名为 `q` 的可选查询参数（如 `http://127.0.0.1:8000/items/foo?q=somequery`）。
    * 因为参数 `q` 被声明为 `= None`，所以它是可选的。
    * 如果没有 `None`，它就是必需的（就像 `PUT` 情况下的请求体）。
* 对于发送到 `/items/{item_id}` 的 `PUT` 请求，把请求体作为 JSON 读取：
    * 检查是否存在必需属性 `name`，且为 `str`。

     * @return the previous value associated with key, or null if no mapping existed
     */
    @Override
    public Object put(final String key, final Object value) {
        return parent.put(key, value);
    }

    /**
     * Removes the mapping for a key from this map if it is present.
     *
     * @param key the key whose mapping is to be removed from the map

    }

    /** Map for normalizing protocols */
    protected static final Map<String, String> CANONICAL_PROTOCOLS = newHashMap();
    static {
        CANONICAL_PROTOCOLS.put("wsjar", "jar"); // Proprietary protocol used by WebSphere for jar files
        CANONICAL_PROTOCOLS.put("vfsfile", "file"); // Proprietary protocol used by JBossAS5 for file system
    }

    /**
     * Opens a URL and returns an {@link InputStream}.
     *

        final Lock acquiredAggregatorLock;
        final OwnerReentrantLock acquiredProjectLock;

        ProjectLock(MavenSession session, MojoDescriptor mojoDescriptor) {
            mojos.put(Thread.currentThread(), mojoDescriptor);
            boolean aggregator = mojoDescriptor.isAggregator();
            acquiredAggregatorLock = aggregator ? aggregatorLock.writeLock() : aggregatorLock.readLock();

              Object value = new Object();
              result.put(key, value);
            }
            result.put(extraKey, extraValue);
            result.put(extraValue, null);
            return result;
          }
        };
    LoadingCache<Object, Object> cache = CacheBuilder.newBuilder().build(loader);
    cache.asMap().put(extraKey, extraKey);

                if (!repos.containsKey(repo.getId())) {
                    repos.put(repo.getId(), repo);
                }
            }

            for (ArtifactRepository repo : pomRepositories) {
                if (!repos.containsKey(repo.getId())) {
                    repos.put(repo.getId(), repo);
                }
            }

    public ScriptExecutor() {
        super();
    }

    @Override
    public Object execute(final String scriptType, final String script) {
        final Map<String, Object> params = new HashMap<>();
        params.put("executor", this);

        return ComponentUtil.getScriptEngineFactory().getScriptEngine(scriptType).evaluate(script, params);
    }

                    if (queryMap == null) {
                        queryMap = new HashMap<>();
                        keyMatchQueryMap.put(virtualHost, queryMap);
                    }
                    final String termKey = toLowerCase(keyMatch.getTerm());

    return delegate.pollFirstEntry();
  }

  @Override
  public @Nullable Entry<K, V> pollLastEntry() {
    return delegate.pollLastEntry();
  }

  @Override
  public @Nullable V put(K key, V value) {
    return delegate.put(checkValid(key), value);
  }

  @Override
  public void putAll(Map<? extends K, ? extends V> map) {
    for (K key : map.keySet()) {
      checkValid(key);
    }

	}

	return f
}

type bufPool struct {
	sz   int
	pool bpool.Pool[*[]byte]
}

func (b *bufPool) Put(buf []byte) {
	if cap(buf) < b.sz || cap(buf) > b.sz*2 {
		// Buffer too small or will likely leak memory after being expanded.
		// Drop it.
		return
	}
	b.pool.Put(&buf)
}

func (b *bufPool) Get() []byte {
	bufp := b.pool.Get()
	if bufp == nil || cap(*bufp) < b.sz {