* O mesmo com `app/routers/users.py`,  ele é outro submódulo: `app.routers.users`.
* Há também um subdiretório `app/internal/` com outro arquivo `__init__.py`, então ele é outro "subpacote Python":`app.internal`.
* E o arquivo `app/internal/admin.py` é outro submódulo: `app.internal.admin`.

<img src="/img/tutorial/bigger-applications/package.svg">

A mesma estrutura de arquivos com comentários:

```
.

      Request.Builder()
        .url("https://sni.cloudflaressl.com/cdn-cgi/trace")
        .header("Host", "cloudflare-dns.com")
        .build()
    client.newCall(request).execute().use { response ->
      assertThat(response.code).isEqualTo(200)
      assertThat(response.protocol).isEqualTo(Protocol.HTTP_2)

      assertThat(response.body.string()).contains("h=cloudflare-dns.com")
    }
  }

  @Test
  fun getWithDns() {

import static java.util.Arrays.asList;

import com.google.common.annotations.GwtCompatible;
import com.google.common.collect.testing.AbstractCollectionTester;
import com.google.common.collect.testing.MinimalCollection;
import com.google.common.collect.testing.features.CollectionFeature;
import com.google.common.collect.testing.features.CollectionSize;
import java.util.Collection;

import com.google.common.base.Function;
import com.google.common.base.Throwables;
import com.google.common.collect.Lists;
import com.google.common.reflect.AbstractInvocationHandler;
import com.google.common.reflect.Reflection;
import com.google.errorprone.annotations.CanIgnoreReturnValue;
import java.lang.reflect.AccessibleObject;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;

 * limitations under the License.
 */

package com.google.common.collect.testing;

import static com.google.common.collect.testing.Helpers.copyToList;
import static com.google.common.collect.testing.features.CollectionFeature.DESCENDING_VIEW;
import static com.google.common.collect.testing.features.CollectionFeature.SUBSET_VIEW;

import com.google.common.annotations.GwtIncompatible;

 * limitations under the License.
 */

package com.google.common.collect;

import static com.google.common.collect.MoreCollectors.onlyElement;

import com.google.caliper.BeforeExperiment;
import com.google.caliper.Benchmark;
import com.google.caliper.Param;
import com.google.caliper.api.SkipThisScenarioException;
import java.util.ArrayList;
import java.util.Collection;

## Um aplicativo com callbacks

Vamos ver tudo isso com um exemplo.

Imagine que você tem um aplicativo que permite criar faturas.

Essas faturas terão um `id`, `title` (opcional), `customer` e `total`.

O usuário da sua API (um desenvolvedor externo) criará uma fatura em sua API com uma solicitação POST.

Então sua API irá (vamos imaginar):

 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.google.common.collect;

import static com.google.common.collect.DiscreteDomain.integers;

import com.google.caliper.BeforeExperiment;
import com.google.caliper.Benchmark;
import com.google.caliper.Param;
import java.util.Set;

/**
 * Very simple powerSet iteration benchmark.
 *

 */

package com.google.common.math;

import static com.google.common.math.MathBenchmarking.ARRAY_MASK;
import static com.google.common.math.MathBenchmarking.ARRAY_SIZE;
import static com.google.common.math.MathBenchmarking.RANDOM_SOURCE;
import static java.math.RoundingMode.CEILING;

import com.google.caliper.BeforeExperiment;
import com.google.caliper.Benchmark;
import com.google.caliper.Param;

      "source": {
        "git": {
          "remote": "https://github.com/grafana/grafonnet.git",
          "subdir": "gen/grafonnet-latest"
        }
      },
      "version": "18eb4e529c60ec20ab243e2da3bcb52b2fd0d223",
      "sum": "eyuJ0jOXeA4MrobbNgU4/v5a7ASDHslHZ0eS6hDdWoI="
    },
    {
      "source": {
        "git": {
          "remote": "https://github.com/grafana/grafonnet.git",
          "subdir": "gen/grafonnet-v11.0.0"