code: def get_plugins(self, plugin_type=None):
          
          if plugin_type is None:
              return self.plugins.values()
  
          plugin_list = []
          for name, plugin in self.plugins.items():
              if isinstance(plugin, plugin_type if inspect.isclass(plugin_type) else type(plugin_type)):
                  plugin_list.append(plugin)
  
          return plugin_list
docs: Retrieve a list of plugins in the PluginManager.
          All plugins if no arguments are provides, or of the specified type.
          :param plugin_type: list: Types of plugins to retrieve from the plugin manager.
          :return: Plugins being managed by the Manager (optionally of the desired plugin_type).
          :rtype: list