When you want to call an `async def` function, you have to "await" it. So, this won't work:

```Python
# This won't work, because get_burgers was defined with: async def
burgers = get_burgers(2)
```

---

    val client =
      OkHttpClient.Builder()
        .connectionPool(poolApi)
        .build()
    val call = client.newCall(Request(addressA.url)) as RealCall
    call.enterNetworkInterceptorExchange(call.request(), true, factory.newChain(call))
    c1.withLock { call.acquireConnectionNoEvents(c1) }

    // Running at time 50, the pool returns that nothing can be evicted until time 150.

    /** Do this task's work, and then start another, such as by calling [startNextTask]. */
    fun start()
  }

  private object TestThreadSerialTask : SerialTask {
    override fun start() = error("unexpected call")
  }

  inner class RunnableSerialTask(
    private val runnable: Runnable,
  ) : SerialTask {
    override fun start() {
      taskRunner.assertThreadHoldsLock()
      require(currentTask == this)

  private var nextQueueName = 10000
  private var coordinatorWaiting = false
  private var coordinatorWakeUpAt = 0L

  /**
   * When we need a new thread to run tasks, we call [Backend.execute]. A few microseconds later we
   * expect a newly-started thread to call [Runnable.run]. We shouldn't request new threads until
   * the already-requested ones are in service, otherwise we might create more threads than we need.
   *

!!! tip
    We only need to create one `PeeweeGetterDict` class, and we can use it in all the Pydantic *models* / schemas.

## CRUD utils

Now let's see the file `sql_app/crud.py`.

### Create all the CRUD utils

Create all the same CRUD utils as in the SQLAlchemy tutorial, all the code is very similar:

```Python hl_lines="1  4-5  8-9  12-13  16-20  23-24  27-30"

        .build()
    val latch = CountDownLatch(1)
    val exceptionRef = AtomicReference<Throwable>()
    val call = client.newCall(request)
    call.timeout().timeout(250, TimeUnit.MILLISECONDS)
    call.enqueue(
      object : Callback {
        override fun onFailure(
          call: Call,
          e: IOException,
        ) {
          exceptionRef.set(e)
          latch.countDown()
        }

        localhostIpv4,
        localhostIpv6,
      )
    serverIpv4.enqueue(
      MockResponse(body = "unexpected call to IPv4"),
    )
    serverIpv6.enqueue(
      MockResponse(body = "hello from IPv6"),
    )

    val call = client.newCall(Request(url))
    val response = call.execute()
    assertThat(response.body.string()).isEqualTo("hello from IPv6")

        .build()
    val call = client.newCall(request1)
    assertFailsWith<SocketTimeoutException> {
      call.execute() // we want this call to throw a SocketTimeoutException
    }
  }

  @Test
  fun chainCanCancelCall() {
    val callRef = AtomicReference<Call>()
    val interceptor =
      Interceptor { chain: Interceptor.Chain ->
        val call = chain.call()
        callRef.set(call)

 * [close()][Response.close] for you.
 *
 * ```java
 * Call call = client.newCall(request);
 * try (Response response = call.execute()) {
 * ... // Use the response.
 * }
 * ```
 *
 * You can use a similar block for asynchronous calls:
 *
 * ```java
 * Call call = client.newCall(request);
 * call.enqueue(new Callback() {
 *   public void onResponse(Call call, Response response) throws IOException {

        type = TYPE_RST_STREAM,
        flags = FLAG_NONE,
      )
      sink.writeInt(errorCode.httpCode)
      sink.flush()
    }
  }

  /** The maximum size of bytes that may be sent in a single call to [data]. */
  fun maxDataLength(): Int = maxFrameSize

  /**
   * `source.length` may be longer than the max length of the variant's data frame. Implementations
   * must send multiple frames as necessary.
   *