<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def default_hass_config_dir():
 """Put together the default configuration directory based on the OS."""

    data_dir = os.getenv("APPDATA") if os.name == "nt" else os.path.expanduser("~")
    return os.path.join(data_dir, ".homeassistant")