docs: def insert_concurrent_execution_histories(self, parent, concurrent_execution_histories):
          """Adds the child execution histories of a concurrency state.
  
          :param Gtk.TreeItem parent: the parent to add the next history item to
          :param list[ExecutionHistory] concurrent_execution_histories: a list of all child execution histories
          :return:
          """
          for execution_history in concurrent_execution_histories:
              if len(execution_history) >= 1:
                  first_history_item = execution_history[0]
                  # this is just a dummy item to have an extra parent for each branch
                  # gives better overview in case that one of the child state is a simple execution state
                  tree_item = self.insert_history_item(parent, first_history_item, "Concurrency Branch", dummy=True)
                  self.insert_execution_history(tree_item, execution_history)