docs: def system_config_dir():
      r"""Return the system-wide config dir (full path).
  
      - Linux, SunOS: /etc/glances
      - *BSD, macOS: /usr/local/etc/glances
      - Windows: %APPDATA%\glances
      """
      if LINUX or SUNOS:
          path = '/etc'
      elif BSD or MACOS:
          path = '/usr/local/etc'
      else:
          path = os.environ.get('APPDATA')
      if path is None:
          path = ''
      else:
          path = os.path.join(path, 'glances')
  
      return path