'Get a list of config file paths.
The list is built taking into account of the OS, priority and location.
* custom path: /path/to/glances
* Linux, SunOS: ~/.config/glances, /etc/glances
* *BSD: ~/.config/glances, /usr/local/etc/glances
* macOS: ~/Library/Application Support/glances, /usr/local/etc/glances
* Windows: %APPDATA%\glances
The config file will be searched in the following order of priority:
* /path/to/file (via -C flag)
* user\'s home directory (per-user settings)
* system-wide directory (system-wide settings)'

def config_file_paths(self):

    paths = []
    if self.config_dir:
        paths.append(self.config_dir)
    paths.append(os.path.join(user_config_dir(), self.config_filename))
    paths.append(os.path.join(system_config_dir(), self.config_filename))
    return paths
