'Enable and initialize a stanza plugin.
:param string attrib: The :attr:`plugin_attrib` value of the
plugin to enable.'

def init_plugin(self, attrib, lang=None, existing_xml=None, reuse=True):

    default_lang = self.get_lang()
    if (not lang):
        lang = default_lang
    plugin_class = self.plugin_attrib_map[attrib]
    if (plugin_class.is_extension and ((attrib, None) in self.plugins)):
        return self.plugins[(attrib, None)]
    if (reuse and ((attrib, lang) in self.plugins)):
        return self.plugins[(attrib, lang)]
    plugin = plugin_class(parent=self, xml=existing_xml)
    if plugin.is_extension:
        self.plugins[(attrib, None)] = plugin
    else:
        if (lang != default_lang):
            plugin[u'lang'] = lang
        self.plugins[(attrib, lang)] = plugin
    if (plugin_class in self.plugin_iterables):
        self.iterables.append(plugin)
        if plugin_class.plugin_multi_attrib:
            self.init_plugin(plugin_class.plugin_multi_attrib)
    self.loaded_plugins.add(attrib)
    return plugin
