def ListInstances(args: 'argparse.Namespace') -> None:
  """List EC2 instances in AWS account.

  Args:
    args (argparse.Namespace): Arguments from ArgumentParser.
  """

  aws_account = account.AWSAccount(args.zone)
  instances = aws_account.ec2.ListInstances()

  logger.info('Instances found:')
  for instance_name, instance in instances.items():
    boot_volume = instance.GetBootVolume().volume_id
    logger.info(
        'Name: {0:s}, Boot volume: {1:s}'.format(instance_name, boot_volume))
List EC2 instances in AWS account.

Args:
args (argparse.Namespace): Arguments from ArgumentParser.
tools/aws_cli.py