def _get_default_directory():
return os.environ.get('<STR_LIT>') or os.path.join(<EOL>os.environ.get('<STR_LIT>') or os.path.expanduser('<STR_LIT>'),<EOL>'<STR_LIT>',<EOL>)<EOL>
Returns the default directory for the Store.  This is intentionally
    underscored to indicate that `Store.get_default_directory` is the intended
    way to get this information.  This is also done so
    `Store.get_default_directory` can be mocked in tests and
    `_get_default_directory` can be tested.