# -*- coding: utf-8 -*-
"""Utility module for command line argument parsing"""

from argparse import ArgumentParser, FileType


def parent_parser():
    """Create command line argument parser with common PostgreSQL options

    :return: the created parser
    """
    parser = ArgumentParser(add_help=False)
    parser.add_argument('dbname', help='database name')
    group = parser.add_argument_group('Connection options')
    group.add_argument('-H', '--host', help="database server host or "
                        "socket directory (default %(default)s)")
    group.add_argument('-p', '--port', type=int, help="database server port "
                        "number (default %(default)s)")
    group.add_argument('-U', '--username', dest='user',
                        help="database user name (default %(default)s)")
    group.add_argument('-W', '--password', action="store_true",
                        help="force password prompt")
    parser.add_argument('-o', '--output', type=FileType('w'),
                        help="output file name (default stdout)")
    parser.add_argument('--version', action='version', version='%(prog)s 0.4')
    return parser

# -*- coding: utf-8 -*-
"""Utility module for command line argument parsing"""

from argparse import ArgumentParser, FileType


def parent_parser():
    """Create command line argument parser with common PostgreSQL options

    :return: the created parser
    """
    parser = ArgumentParser(add_help=False)
    parser.add_argument('dbname', help='database name')
    group = parser.add_argument_group('Connection options')
    group.add_argument('-H', '--host', help="database server host or "
                        "socket directory (default %(default)s)")
    group.add_argument('-p', '--port', type=int, help="database server port "
                        "number (default %(default)s)")
    group.add_argument('-U', '--username', dest='username',
                        help="database user name (default %(default)s)")
    group.add_argument('-W', '--password', action="store_true",
                        help="force password prompt")
    parser.add_argument('-o', '--output', type=FileType('w'),
                        help="output file name (default stdout)")
    parser.add_argument('--version', action='version', version='%(prog)s 0.4')
    return parser

Change 'username' destination to the 'username' attribute instead of user, since that's what is used in the code.
Change 'username' destination to the 'username' attribute instead of user, since that's what is used in the code.