docs: def list():
          """Return a list of all time zones known to the system."""
          handle = winreg.ConnectRegistry(None, winreg.HKEY_LOCAL_MACHINE)
          tzkey = winreg.OpenKey(handle, TZKEYNAME)
          result = [winreg.EnumKey(tzkey, i)
                    for i in range(winreg.QueryInfoKey(tzkey)[0])]
          tzkey.Close()
          handle.Close()
          return result