'Caches the plugin instance.
:param path: where the user is in the plugin tree
:return The plugin'

def _get_plugin_inst(self, path):

    try:
        return self.plugin_instances[path]
    except KeyError:
        pass
    if (len(path) == 1):
        return None
    pname = self.treestore[path][3]
    ptype = self.treestore[path[:1]][3]
    plugin = self.w3af.plugins.get_plugin_inst(ptype, pname)
    plugin.pname = pname
    plugin.ptype = ptype
    self.plugin_instances[path] = plugin
    return plugin
