Let's say you have a file structure like this:

```
.
├── app
│   ├── __init__.py
│   ├── main.py
│   ├── dependencies.py
│   └── routers
│   │   ├── __init__.py
│   │   ├── items.py
│   │   └── users.py
│   └── internal
│       ├── __init__.py
│       └── admin.py
```

!!! tip
    There are several `__init__.py` files: one in each directory or subdirectory.

import org.codelibs.fess.helper.PathMappingHelper;
import org.codelibs.fess.helper.SystemHelper;
import org.codelibs.fess.mylasta.direction.FessConfig;
import org.codelibs.fess.unit.UnitFessTestCase;
import org.codelibs.fess.util.ComponentUtil;
import org.codelibs.fess.util.MemoryUtil;
import org.codelibs.nekohtml.parsers.DOMParser;
import org.lastaflute.di.core.exception.ComponentNotFoundException;

		return errors.New("username and password should be set in pairs")
	}

	return nil
}

// ElasticsearchTarget - Elasticsearch target.
type ElasticsearchTarget struct {
	initOnce once.Init

	id         event.TargetID
	args       ElasticsearchArgs
	client     esClient
	store      store.Store[event.Event]
	loggerOnce logger.LogOnce
	quitCh     chan struct{}
}

        SecretKeySpec dataKey = new SecretKeySpec(dataHmac, KerberosConstants.RC4_ALGORITHM);

        cipher = Cipher.getInstance(KerberosConstants.RC4_ALGORITHM);
        cipher.init(Cipher.DECRYPT_MODE, dataKey);

        int plainDataLength = data.length - KerberosConstants.CHECKSUM_SIZE;
        byte[] plainData = cipher.doFinal(data, KerberosConstants.CHECKSUM_SIZE, plainDataLength);

      } else if (busy == 0 && cells == as && casBusy()) {
        boolean init = false;
        try { // Initialize table
          if (cells == as) {
            Cell[] rs = new Cell[2];
            rs[h & 1] = new Cell(x);
            cells = rs;
            init = true;
          }
        } finally {
          busy = 0;
        }
        if (init) break;

        str,
        Doc(
            """
            The HTTP authorization credentials extracted from the header value.
            """
        ),
    ]


class HTTPBase(SecurityBase):
    def __init__(
        self,
        *,
        scheme: str,
        scheme_name: Optional[str] = None,
        description: Optional[str] = None,
        auto_error: bool = True,
    ):

        TrustManagerFactory.getInstance(TrustManagerFactory.getDefaultAlgorithm()).apply {
          init(null as KeyStore?)
        }.trustManagers.first() as X509TrustManager

      val sslContext =
        Platform.get().newSSLContext().apply {
          // TODO remove most of this code after https://github.com/bcgit/bc-java/issues/686
          init(null, arrayOf(trustManager), SecureRandom())
        }

      client =

## 一个文件结构示例

假设你的文件结构如下：

```
.
├── app
│   ├── __init__.py
│   ├── main.py
│   ├── dependencies.py
│   └── routers
│   │   ├── __init__.py
│   │   ├── items.py
│   │   └── users.py
│   └── internal
│       ├── __init__.py
│       └── admin.py
```

!!! tip
    上面有几个 `__init__.py` 文件：每个目录或子目录中都有一个。

    这就是能将代码从一个文件导入到另一个文件的原因。

    例如，在 `app/main.py` 中，你可以有如下一行：

import org.codelibs.fess.es.config.exentity.PathMapping;
import org.codelibs.fess.mylasta.direction.FessConfig;
import org.codelibs.fess.unit.UnitFessTestCase;
import org.codelibs.fess.util.ComponentUtil;
import org.dbflute.optional.OptionalThing;

public class ViewHelperTest extends UnitFessTestCase {
    public ViewHelper viewHelper;

    private UserAgentHelper userAgentHelper;

    private PathMappingHelper pathMappingHelper;

		if k.QueueDir == "" {
			return errors.New("batch should be enabled only if queue dir is enabled")
		}
	}
	return nil
}

// KafkaTarget - Kafka target.
type KafkaTarget struct {
	initOnce once.Init

	id         event.TargetID
	args       KafkaArgs
	client     sarama.Client
	producer   sarama.SyncProducer
	config     *sarama.Config
	store      store.Store[event.Event]