* 文件 `app/routers/items.py` 位于 `app/routers/` 包中，因此它是一个子模块：`app.routers.items`。
* 同样适用于 `app/routers/users.py`，它是另一个子模块：`app.routers.users`。
* 还有一个子目录 `app/internal/` 包含另一个 `__init__.py` 文件，因此它是又一个「Python 子包」：`app.internal`。
* `app/internal/admin.py` 是另一个子模块：`app.internal.admin`。

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

带有注释的同一文件结构：

```bash
.
├── app                  # 「app」是一个 Python 包

	"strings"
	"time"

	"github.com/minio/minio/internal/bpool"
)

const defaultFlushInterval = time.Duration(100) * time.Millisecond

// Forwarder forwards all incoming HTTP requests to configured transport.
type Forwarder struct {
	RoundTripper http.RoundTripper
	PassHost     bool
	Logger       func(error)
	ErrorHandler func(http.ResponseWriter, *http.Request, error)

	// internal variables
	rewriter *headerRewriter
}

import okhttp3.internal.url.PASSWORD_ENCODE_SET
import okhttp3.internal.url.PATH_SEGMENT_ENCODE_SET
import okhttp3.internal.url.PATH_SEGMENT_ENCODE_SET_URI
import okhttp3.internal.url.QUERY_COMPONENT_ENCODE_SET
import okhttp3.internal.url.QUERY_COMPONENT_ENCODE_SET_URI
import okhttp3.internal.url.QUERY_COMPONENT_REENCODE_SET
import okhttp3.internal.url.QUERY_ENCODE_SET
import okhttp3.internal.url.USERNAME_ENCODE_SET
import okhttp3.internal.url.canonicalize

 * limitations under the License.
 */
package okhttp3.internal.connection

import okhttp3.Call
import okhttp3.Connection
import okhttp3.Route
import okio.IOException

/**
 * Listener for connection events. Extend this class to monitor the new connections and closes.
 *
 * All event methods must execute fast, without external locking, cannot throw exceptions,

#include "tensorflow/c/tf_tensor.h"
#include "tensorflow/core/platform/tensor_float_32_utils.h"
#include "tensorflow/core/platform/test.h"

namespace tensorflow {
namespace gradients {
namespace internal {
namespace {

using tensorflow::TF_StatusPtr;

void CompareNumericalAndManualGradients(
    Model model, AbstractContext* ctx,
    absl::Span<AbstractTensorHandle* const> inputs, int input_index,

 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package okhttp3.internal.http2

import assertk.fail
import okio.BufferedSource
import okio.ByteString

internal open class BaseTestHandler : Http2Reader.Handler {
  override fun data(
    inFinished: Boolean,
    streamId: Int,
    source: BufferedSource,
    length: Int,

 * limitations under the License.
 */
package okhttp3.internal.publicsuffix

import java.net.IDN
import okhttp3.internal.and
import okio.ByteString
import okio.ByteString.Companion.encodeUtf8

/**
 * A database of public suffixes provided by [publicsuffix.org][publicsuffix_org].
 *
 * [publicsuffix_org]: https://publicsuffix.org/
 */
class PublicSuffixDatabase internal constructor(
  private val publicSuffixList: PublicSuffixList,

 * Side Public License, v 1.
 */

package org.elasticsearch.gradle.internal.release;

import org.elasticsearch.gradle.Version;
import org.elasticsearch.gradle.VersionProperties;
import org.elasticsearch.gradle.internal.conventions.precommit.PrecommitTaskPlugin;
import org.elasticsearch.gradle.internal.precommit.ValidateYamlAgainstSchemaTask;
import org.gradle.api.Plugin;
import org.gradle.api.Project;

 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package okhttp3.internal.idn

import kotlin.math.abs
import okio.ByteString

internal sealed interface MappedRange {
  val rangeStart: Int

  data class Constant(
    override val rangeStart: Int,
    val type: Int,
  ) : MappedRange {
    val b1: Int

    into(kotlinTemplatesOutput)

    filteringCharset = Charsets.UTF_8.toString()

    expand(
      "projectVersion" to project.version.toString(),
    )
  }

// Build & use okhttp3/internal/idn/IdnaMappingTableInstance.kt
val generateIdnaMappingTableConfiguration: Configuration by configurations.creating
dependencies {
  generateIdnaMappingTableConfiguration(projects.okhttpIdnaMappingTable)
}