{!../../../docs_src/custom_response/tutorial008.py!}
```

1. This is the generator function. It's a "generator function" because it contains `yield` statements inside.
2. By using a `with` block, we make sure that the file-like object is closed after the generator function is done. So, after it finishes sending the response.

    address: Address,
    connectionUser: ConnectionUser,
    routes: List<Route>?,
    requireMultiplexed: Boolean,
  ): RealConnection? {
    for (connection in connections) {
      // In the first synchronized block, acquire the connection if it can satisfy this call.
      val acquired =
        connection.withLock {
          when {
            requireMultiplexed && !connection.isMultiplexed -> false

## Privileges required

      )
    }
    handler.windowUpdate(streamId, increment)
  }

  @Throws(IOException::class)
  override fun close() {
    source.close()
  }

  /**
   * Decompression of the header block occurs above the framing layer. This class lazily reads
   * continuation frames as they are needed by [Hpack.Reader.readHeaders].
   */
  internal class ContinuationSource(
    private val source: BufferedSource,

/*
 * Copyright (C) 2023 Block, Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,

```Python
async with lifespan(app):
    await do_stuff()
```

When you create a context manager or an async context manager like above, what it does is that, before entering the `with` block, it will execute the code before the `yield`, and after exiting the `with` block, it will execute the code after the `yield`.

In our code example above, we don't use it directly, but we pass it to FastAPI for it to use it.

  private lateinit var server: MockWebServer
  private lateinit var client: OkHttpClient

  @BeforeEach
  fun setUp() {
    // Sockets on some platforms can have large buffers that mean writes do not block when
    // required. These socket factories explicitly set the buffer sizes on sockets created.
    server = MockWebServer()
    server.serverSocketFactory =
      object : DelegatingServerSocketFactory(getDefault()) {

        streamId = 0,
        length = 0,
        type = TYPE_SETTINGS,
        flags = FLAG_ACK,
      )
      sink.flush()
    }
  }

  /**
   * HTTP/2 only. Send a push promise header block.
   *
   * A push promise contains all the headers that pertain to a server-initiated request, and a
   * `promisedStreamId` to which response frames will be delivered. Push promise frames are sent as

/*
 * Copyright (C) 2022 Block, Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,

       - To enable the benefit of incremental builds, we can ask Gradle
       to ignore these two files when considering whether the classpath
       has changed. That is the purpose of this normalization block.
   */
    ignore("okhttp3/osgi/workspace/cnf/repo/index.xml.gz")
    ignore("okhttp3/osgi/workspace/cnf/repo/index.xml.gz.sha")
  }
}

// Expose OSGi jars to the test environment.