How to use the cibuildwheel.util.download function in cibuildwheel

def install_pypy(version: str, arch: str, url: str) -> Path:
    assert arch == '32'
    # Inside the PyPy zip file is a directory with the same name
    zip_filename = url.rsplit('/', 1)[-1]
    extension = ".zip"
    assert zip_filename.endswith(extension)
    installation_path = Path('C:\\cibw') / zip_filename[:-len(extension)]
    if not installation_path.exists():
        pypy_zip = Path('C:\\cibw') / zip_filename
        download(url, pypy_zip)
        # Extract to the parent directory because the zip file still contains a directory
        extract_zip(pypy_zip, installation_path.parent)
        pypy_exe = 'pypy3.exe' if version[0] == '3' else 'pypy.exe'
        (installation_path / 'python.exe').symlink_to(installation_path / pypy_exe)
    return installation_path

def install_pypy(version: str, url: str) -> Path:
    pypy_tar_bz2 = url.rsplit('/', 1)[-1]
    extension = ".tar.bz2"
    assert pypy_tar_bz2.endswith(extension)
    pypy_base_filename = pypy_tar_bz2[:-len(extension)]
    installation_path = Path('/tmp') / pypy_base_filename
    if not installation_path.exists():
        downloaded_tar_bz2 = Path("/tmp") / pypy_tar_bz2
        download(url, downloaded_tar_bz2)
        call(['tar', '-C', '/tmp', '-xf', str(downloaded_tar_bz2)])

    installation_bin_path = installation_path / 'bin'
    python_executable = 'pypy3' if version[0] == '3' else 'pypy'
    pip_executable = 'pip3' if version[0] == '3' else 'pip'
    make_symlinks(installation_bin_path, python_executable, pip_executable)

    return installation_bin_path

def setup_python(python_configuration: PythonConfiguration, dependency_constraint_flags: List[str], environment: ParsedEnvironment) -> Dict[str, str]:
    nuget = Path('C:\\cibw\\nuget.exe')
    if not nuget.exists():
        download('https://dist.nuget.org/win-x86-commandline/latest/nuget.exe', nuget)

    if python_configuration.identifier.startswith('cp'):
        installation_path = install_cpython(python_configuration.version, python_configuration.arch, nuget)
    elif python_configuration.identifier.startswith('pp'):
        assert python_configuration.url is not None
        installation_path = install_pypy(python_configuration.version, python_configuration.arch, python_configuration.url)
    else:
        raise ValueError("Unknown Python implementation")

    assert (installation_path / 'python.exe').exists()

    # set up PATH and environment variables for run_with_env
    env = os.environ.copy()
    env['PYTHON_VERSION'] = python_configuration.version
    env['PYTHON_ARCH'] = python_configuration.arch
    env['PATH'] = os.pathsep.join([

def install_cpython(version: str, url: str) -> Path:
    installed_system_packages = subprocess.check_output(['pkgutil', '--pkgs'], universal_newlines=True).splitlines()

    # if this version of python isn't installed, get it from python.org and install
    python_package_identifier = f'org.python.Python.PythonFramework-{version}'
    if python_package_identifier not in installed_system_packages:
        # download the pkg
        download(url, Path('/tmp/Python.pkg'))
        # install
        call(['sudo', 'installer', '-pkg', '/tmp/Python.pkg', '-target', '/'])
        # patch open ssl
        if version == '3.5':
            open_ssl_patch_url = f'https://github.com/mayeut/patch-macos-python-openssl/releases/download/v1.0.2u/patch-macos-python-{version}-openssl-v1.0.2u.tar.gz'
            download(open_ssl_patch_url, Path('/tmp/python-patch.tar.gz'))
            call(['sudo', 'tar', '-C', f'/Library/Frameworks/Python.framework/Versions/{version}/', '-xmf', '/tmp/python-patch.tar.gz'])

    installation_bin_path = Path(f'/Library/Frameworks/Python.framework/Versions/{version}/bin')
    python_executable = 'python3' if version[0] == '3' else 'python'
    pip_executable = 'pip3' if version[0] == '3' else 'pip'
    make_symlinks(installation_bin_path, python_executable, pip_executable)

    return installation_bin_path

def install_cpython(version: str, url: str) -> Path:
    installed_system_packages = subprocess.check_output(['pkgutil', '--pkgs'], universal_newlines=True).splitlines()

    # if this version of python isn't installed, get it from python.org and install
    python_package_identifier = f'org.python.Python.PythonFramework-{version}'
    if python_package_identifier not in installed_system_packages:
        # download the pkg
        download(url, Path('/tmp/Python.pkg'))
        # install
        call(['sudo', 'installer', '-pkg', '/tmp/Python.pkg', '-target', '/'])
        # patch open ssl
        if version == '3.5':
            open_ssl_patch_url = f'https://github.com/mayeut/patch-macos-python-openssl/releases/download/v1.0.2u/patch-macos-python-{version}-openssl-v1.0.2u.tar.gz'
            download(open_ssl_patch_url, Path('/tmp/python-patch.tar.gz'))
            call(['sudo', 'tar', '-C', f'/Library/Frameworks/Python.framework/Versions/{version}/', '-xmf', '/tmp/python-patch.tar.gz'])

    installation_bin_path = Path(f'/Library/Frameworks/Python.framework/Versions/{version}/bin')
    python_executable = 'python3' if version[0] == '3' else 'python'
    pip_executable = 'pip3' if version[0] == '3' else 'pip'
    make_symlinks(installation_bin_path, python_executable, pip_executable)

    return installation_bin_path