def METHOD_NAME(folder):
    """Return folder/drive free space (in bytes)."""
    import platform
    if platform.system() == 'Windows':
        import ctypes
        free_bytes = ctypes.c_ulonglong(0)
        ctypes.windll.kernel32.GetDiskFreeSpaceExW(ctypes.c_wchar_p(folder), None, None, ctypes.pointer(free_bytes))
        free_space = free_bytes.value
    else:
        free_space = os.statvfs(folder).f_bfree
    LOGGER.debug('Free space: {}'.format(free_space))
    return free_space