* </ul>
 *
 * The last point is subtle. Often the observable object will be managing its own internal state
 * using a lock, however it is dangerous to dispatch listeners while holding a lock because they
 * might run on the {@code directExecutor()} or be otherwise re-entrant (call back into your
 * object). So it is important to not call {@link #dispatch} while holding any locks. This is why

.idea
.ipynb_checkpoints
.mypy_cache
.vscode
__pycache__
.pytest_cache
htmlcov
dist
site
.coverage*
coverage.xml
.netlify
test.db
log.txt
Pipfile.lock
env3.*
env
docs_build
site_build
venv
docs.zip
archive.zip

# vim temporary files
*~
.*.sw?
.cache

# macOS

/*
 * Copyright (C) 2025 Block, Inc.
 *
 * 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
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,

/*
 * Copyright (C) 2024 Block, Inc.
 *
 * 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
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,

/*
 * Copyright (C) 2025 Block, Inc.
 *
 * 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
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,

/*
 * Copyright (C) 2023 Block, Inc.
 *
 * 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
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,

import java.util.Spliterator;
import java.util.stream.Stream;
import org.jspecify.annotations.NullUnmarked;
import org.jspecify.annotations.Nullable;

/**
 * {@link Set} implementation that asserts that a given lock is held whenever one of its methods is
 * called.
 */
@NullUnmarked
class LockHeldAssertingSet<E> extends ForwardingSet<E> implements Serializable {
  final Set<E> delegate;
  final Object mutex;

    private static final long serialVersionUID = 1L;

    /**
     * Resource type that caused the error
     */
    public enum ResourceType {
        FILE_HANDLE, CONNECTION, MEMORY, DISK_SPACE, QUOTA, LOCK, BUFFER, THREAD_POOL
    }

    private final ResourceType resourceType;
    private final long availableResources;
    private final long requestedResources;

    /**
     * Creates a resource exception
     *

    protected int parameterOffset;
    /** Displacement of these parameter bytes from the start of the total parameter block */
    protected int parameterDisplacement;
    /** Offset from the start of the SMB header to the data bytes */
    protected int dataOffset;
    /** Displacement of these data bytes from the start of the total data block */
    protected int dataDisplacement;
    /** Number of setup words in this response */

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

When you create a context manager or an async context manager like above, what it does is that, before entering the `with` block, it will execute the code before the `yield`, and after exiting the `with` block, it will execute the code after the `yield`.

In our code example above, we don't use it directly, but we pass it to FastAPI for it to use it.