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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def add_settings_parser(subparsers, parent_parser):
 """Creates the args parser needed for the settings command and its subcommands. """

    # The following parser is for the settings subsection of commands.  These
    # commands display information about the currently applied on-chain
    # settings.

    settings_parser = subparsers.add_parser(
        'settings',
        help='Displays on-chain settings',
        description='Displays the values of currently active on-chain '
                    'settings.')

    settings_parsers = settings_parser.add_subparsers(
        title='settings',
        dest='settings_cmd')
    settings_parsers.required = True

    list_parser = settings_parsers.add_parser(
        'list',
        help='Lists the current keys and values of on-chain settings',
        description='List the current keys and values of on-chain '
                    'settings. The content can be exported to various '
                    'formats for external consumption.'
    )

    list_parser.add_argument(
        '--url',
        type=str,
        help="identify the URL of a validator's REST API",
        default='http://localhost:8008')

    list_parser.add_argument(
        '--filter',
        type=str,
        default='',
        help='filters keys that begin with this value')

    list_parser.add_argument(
        '--format',
        default='default',
        choices=['default', 'csv', 'json', 'yaml'],
        help='choose the output format')