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/*
 * Copyright 2012-2025 CodeLibs Project and the Others.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
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 * distributed under the License is distributed on an "AS IS" BASIS,

{* ../../docs_src/events/tutorial003.py hl[1,13] *}

A **context manager** in Python is something that you can use in a `with` statement, for example, `open()` can be used as a context manager:

```Python
with open("file.txt") as file:
    file.read()
```

In recent versions of Python, there's also an **async context manager**. You would use it with `async with`:

```Python
async with lifespan(app):
    await do_stuff()
```

     * Returns <code>true</code> if the class file corresponding to the specified class name exists in the resources handled by this instance.
     * <p>
     * If a root package is specified at instance construction, the specified class name is interpreted as a relative name from the root package.
     * </p>
     *
     * @param className the class name
     * @return <code>true</code> if the class file exists in the resources handled by this instance

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