docs: def pending():
      """Show the number of pending signals by signal type."""
  
      signalbus = current_app.extensions['signalbus']
      pending = []
      total_pending = 0
      for signal_model in signalbus.get_signal_models():
          count = signal_model.query.count()
          if count > 0:
              pending.append((count, signal_model.__name__))
          total_pending += count
      if pending:
          pending.sort()
          max_chars = len(str(pending[-1][0]))
          for n, signal_name in pending:
              click.echo('{} of type "{}"'.format(str(n).rjust(max_chars), signal_name))
      click.echo(25 * '-')
      click.echo('Total pending: {} '.format(total_pending))