When the `with` block finishes, it makes sure to close the file, even if there were exceptions.

When you create a dependency with `yield`, **FastAPI** will internally create a context manager for it, and combine it with some other related tools.

### Using context managers in dependencies with `yield` { #using-context-managers-in-dependencies-with-yield }

/// warning

This is, more or less, an "advanced" idea.

- **MS-SMB2 Section 2.2.24**: SMB2 LEASE_BREAK Acknowledgment

## 3. Lease Types and States

### 3.1 Lease State Flags
```java
public class Smb2LeaseState {
    // Lease state flags (can be combined)
    public static final int SMB2_LEASE_NONE           = 0x00;
    public static final int SMB2_LEASE_READ_CACHING   = 0x01;  // R - Read caching
    public static final int SMB2_LEASE_HANDLE_CACHING = 0x02;  // H - Handle caching  

    checkState(
        this.maximumWeight == UNSET_INT,
        "maximum weight was already set to %s",
        this.maximumWeight);
    checkState(this.weigher == null, "maximum size can not be combined with weigher");
    checkArgument(maximumSize >= 0, "maximum size must not be negative");
    this.maximumSize = maximumSize;
    return this;
  }

  /**

    ImmutableRangeSet.Builder<Integer> zat =
        ImmutableRangeSet.<Integer>builder().add(rangeThree).add(rangeFour);

    ImmutableRangeSet<Integer> rangeSet = zis.combine(zat).build();

    assertThat(rangeSet.asRanges())
        .containsExactly(Range.closedOpen(1, 3), Range.closedOpen(4, 5), Range.closedOpen(6, 9))
        .inOrder();
  }

### Import `FastAPI` { #import-fastapi }

You import and create a `FastAPI` class as normally.

And we can even declare [global dependencies](dependencies/global-dependencies.md){.internal-link target=_blank} that will be combined with the dependencies for each `APIRouter`:

```Python hl_lines="1  3  7" title="app/main.py"
{!../../docs_src/bigger_applications/app/main.py!}
```

### Import the `APIRouter` { #import-the-apirouter }

    Source Code.

    1.5. "Initial Developer" means the individual or entity that first
    makes Original Software available under this License.

    1.6. "Larger Work" means a work which combines Covered Software or
    portions thereof with code not governed by the terms of this License.

    1.7. "License" means this document.

    1.8. "Licensable" means having the right to grant, to the maximum

    ImmutableListMultimap.Builder<String, Integer> zat =
        ImmutableListMultimap.<String, Integer>builder().put("a", 3).put("c", 4);
    ImmutableListMultimap<String, Integer> multimap = zis.combine(zat).build();
    assertThat(multimap.keySet()).containsExactly("a", "b", "c").inOrder();
    assertThat(multimap.values()).containsExactly(1, 3, 2, 4).inOrder();
    assertThat(multimap.get("a")).containsExactly(1, 3).inOrder();

$ python ./scripts/docs.py build-all

Building docs for: en
Building docs for: es
Successfully built docs for: es
```

</div>

This builds all those independent MkDocs sites for each language, combines them, and generates the final output at `./site/`.

Then you can serve that with the command `serve`:

<div class="termy">

```console
// Use the command "serve" after running "build-all"

          <configuration>
            <source>1.8</source>
            <target>1.8</target>
            <encoding>UTF-8</encoding>
            <parameters>true</parameters>
            <compilerArgs combine.children="override">
              <!-- https://errorprone.info/docs/installation#maven -->
              <arg>-XDcompilePolicy=simple</arg>
              <arg>--should-stop=ifError=FLOW</arg>

          <configuration>
            <source>1.8</source>
            <target>1.8</target>
            <encoding>UTF-8</encoding>
            <parameters>true</parameters>
            <compilerArgs combine.children="override">
              <!-- https://errorprone.info/docs/installation#maven -->
              <arg>-XDcompilePolicy=simple</arg>
              <arg>--should-stop=ifError=FLOW</arg>