docs: def load_plugin_from_addonxml(cls, mode, url):
          '''Attempts to import a plugin's source code and find an instance of
          :class:`~xbmcswif2.Plugin`. Returns an instance of PluginManager if
          succesful.
          '''
          cwd = os.getcwd()
          sys.path.insert(0, cwd)
          module_name = get_addon_module_name(os.path.join(cwd, 'addon.xml'))
          addon = __import__(module_name)
  
          # Find the first instance of xbmcswift2.Plugin
          try:
              plugin = (attr_value for attr_value in vars(addon).values()
                        if isinstance(attr_value, Plugin)).next()
          except StopIteration:
              sys.exit('Could\'t find a Plugin instance in %s.py' % module_name)
  
          return cls(plugin, mode, url)