code: def list_tasks(collector, tasks, **kwargs):
      
      print("Available tasks to choose from are:")
      print("Use the --task option to choose one")
      print("")
      keygetter = lambda item: item[1].label
      tasks = sorted(tasks.items(), key=keygetter)
      for label, items in itertools.groupby(tasks, keygetter):
          print("--- {0}".format(label))
          print("----{0}".format("-" * len(label)))
          sorted_tasks = sorted(list(items), key=lambda item: len(item[0]))
          max_length = max(len(name) for name, _ in sorted_tasks)
          for key, task in sorted_tasks:
              desc = dedent(task.description or "").strip().split('\n')[0]
              print("\t{0}{1} :-: {2}".format(" " * (max_length-len(key)), key, desc))
          print("")
docs: List the available_tasks