Actually, all (or most) of the web frameworks work in this same way.

You never call those functions directly. They are called by your framework (in this case, **FastAPI**).

    public int[] batchInsert(List<ScheduledJob> list, RequestOptionCall<BulkRequestBuilder> call) {
        return batchInsert(list, call, null);
    }

    public int[] batchInsert(List<ScheduledJob> list, RequestOptionCall<BulkRequestBuilder> call,
            RequestOptionCall<IndexRequestBuilder> entityCall) {
        return doBatchInsert(new BulkList<>(list, call, entityCall), null);
    }

        .url("http://publicobject.com/helloworld.txt")
        .build();

    client.newCall(request).enqueue(new Callback() {
      @Override public void onFailure(Call call, IOException e) {
        e.printStackTrace();
      }

      @Override public void onResponse(Call call, Response response) throws IOException {
        try (ResponseBody responseBody = response.body()) {

  }

  /** Returns the return type of this {@code Invokable}. */
  // All subclasses are owned by us and we'll make sure to get the R type right.
  @SuppressWarnings("unchecked")
  public final TypeToken<? extends R> getReturnType() {
    return (TypeToken<? extends R>) TypeToken.of(getGenericReturnType());
  }

  /**
   * Returns all declared parameters of this {@code Invokable}. Note that if this is a constructor

        Mall<Outdoor>.Shop<Grocery> shop) {
      return notSubtype(shop);
    }

    @TestSubtype
    public Mall<Outdoor>.Shop<Electronics> innerTypeDoesNotMatch_subtypeWithWildcard(
        Mall<Outdoor>.Shop<? extends Electronics> shop) {
      return notSubtype(shop);
    }

    @TestSubtype

        .addQueryParameter("redirect_uri", redirectUrl.toString())
        .build();
    Request request = new Request.Builder()
        .url(url)
        .build();
    Call call = httpClient.newCall(request);
    try (Response response = call.execute()) {
      JsonAdapter<OAuthSession> jsonAdapter = moshi.adapter(OAuthSession.class);
      return jsonAdapter.fromJson(response.body().source());
    }
  }

        override fun connectionAcquired(
          call: Call,
          connection: Connection,
        ) {
          // We have the connection and it's in the pool. Let request2 proceed to make a connection.
          latch2.countDown()
        }
      }
    val request2Listener: EventListener =
      object : EventListener() {
        override fun connectStart(
          call: Call,
          inetSocketAddress: InetSocketAddress,

   *
   * This can be invoked more than 1 time for a single [Call]. For example, if the response
   * to the [Call.request] is a redirect to a different address.
   */
  open fun connectionAcquired(
    call: Call,
    connection: Connection,
  ) {
  }

  /**
   * Invoked after a connection has been released for the `call`.
   *

   * timeout. Because networks can fail during an exchange, it is possible that the remote server
   * accepted the request before the failure.
   */
  fun onFailure(
    call: Call,
    e: IOException,
  )

  /**
   * Called when the HTTP response was successfully returned by the remote server. The callback may

        .build(),
    )
    val call =
      client.newCall(
        Request.Builder()
          .url(server.url("/"))
          .build(),
      )
    call.enqueue(
      object : Callback {
        override fun onFailure(
          call: Call,
          e: IOException,
        ) {
        }

        override fun onResponse(
          call: Call,
          response: Response,
        ) {