def has_deps(backend: str) -> list[str]:
    """
    Check if the backend has all its dependencies installed.

    Args:
        backend: The backend to check.

    Returns:
        A list of missing dependencies. If this is empty, we can use this backend.
    """
    if backend not in CORES:
        raise QtileError(f"Backend {backend} does not exist")

    not_found = []
    for dep in CORES[backend]:
        if not importlib.util.find_spec(dep):
            not_found.append(dep)

    return not_found

    Check if the backend has all its dependencies installed.

    Args:
        backend: The backend to check.

    Returns:
        A list of missing dependencies. If this is empty, we can use this backend.
    
libqtile/backend/__init__.py