code: def load_custom_tc_plugins(self, plugin_path=None):
          
          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
docs: 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.