<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def user_data_dir(self):
 """Return ``user_data_dir``."""

        directory = appdirs.user_data_dir(self.appname, self.appauthor,
                             version=self.version, roaming=self.roaming)
        if self.create:
            self._ensure_directory_exists(directory)
        return directory