<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def Process(self, parser_mediator, registry_key, **kwargs):
 """Processes a Windows Registry key or value. Args: parser_mediator (ParserMediator):
 mediates interactions between parsers and other components, such as storage and dfvfs. registry_key (dfwinreg.WinRegistryKey):
 Windows Registry key. Raises: ValueError: If the Windows Registry key is not set. """

    if registry_key is None:
      raise ValueError('Windows Registry key is not set.')

    # This will raise if unhandled keyword arguments are passed.
    super(WindowsRegistryPlugin, self).Process(parser_mediator, **kwargs)

    self.ExtractEvents(parser_mediator, registry_key, **kwargs)