def do_block(args):
    """Runs the block list or block show command, printing output to the
    console

        Args:
            args: The parsed arguments sent to the command at runtime
    """
    rest_client = RestClient(args.url, args.user)

    if args.subcommand == 'list':
        block_generator = rest_client.list_blocks()
        blocks = []
        left = args.count
        for block in block_generator:
            blocks.append(block)
            left -= 1
            if left <= 0:
                break

        keys = ('num', 'block_id', 'batches', 'txns', 'signer')
        headers = tuple(k.upper() if k != 'batches' else 'BATS' for k in keys)

        def parse_block_row(block):
            batches = block.get('batches', [])
            txns = [t for b in batches for t in b['transactions']]
            return (
                block['header'].get('block_num', 0),
                block['header_signature'],
                len(batches),
                len(txns),
                block['header']['signer_public_key'])

        if args.format == 'default':
            fmt.print_terminal_table(headers, blocks, parse_block_row)

        elif args.format == 'csv':
            fmt.print_csv(headers, blocks, parse_block_row)

        elif args.format == 'json' or args.format == 'yaml':
            data = [{k: d for k, d in zip(keys, parse_block_row(b))}
                    for b in blocks]

            if args.format == 'yaml':
                fmt.print_yaml(data)
            elif args.format == 'json':
                fmt.print_json(data)
            else:
                raise AssertionError('Missing handler: {}'.format(args.format))

        else:
            raise AssertionError('Missing handler: {}'.format(args.format))

    if args.subcommand == 'show':
        output = rest_client.get_block(args.block_id)

        if args.key:
            if args.key in output:
                output = output[args.key]
            elif args.key in output['header']:
                output = output['header'][args.key]
            else:
                raise CliException(
                    'key "{}" not found in block or header'.format(args.key))

        if args.format == 'yaml':
            fmt.print_yaml(output)
        elif args.format == 'json':
            fmt.print_json(output)
        else:
            raise AssertionError('Missing handler: {}'.format(args.format))