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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def load_custom_tc_plugins(self, plugin_path=None):
 """ Load custom test case level plugins from plugin_path. :param plugin_path: Path to file, which contains the imports and mapping for plugins. :return: None if plugin_path is None or False or something equivalent to those. """

        if not plugin_path:
            return
        directory = os.path.dirname(plugin_path)
        sys.path.append(directory)
        modulename = os.path.split(plugin_path)[1]
        # Strip of file extension.
        if "." in modulename:
            modulename = modulename[:modulename.rindex(".")]
        try:
            module = importlib.import_module(modulename)
        except ImportError:
            raise PluginException("Unable to import custom plugin information from {}.".format(
                plugin_path))
        for plugin_name, plugin_class in module.plugins_to_load.items():
            if issubclass(plugin_class, PluginBase):
                try:
                    self.register_tc_plugins(plugin_name, plugin_class())
                except PluginException as error:
                    self.logger.debug(error)
                    continue