def get_parser_defaults(parser):
    """
    Given an argparse.ArgumentParser pre-configured with args/options via
    add_argument, return a dictionary of {dest: default}, containing the
    options attribute names and their default value.

    :param parser: A pre-configured parser instance.
    :type parser: argparse.ArgumentParser
    :return: A dictionary of {dest: default}, containing the options attribute
             names and their default value
    :rtype: dict
    """
    defaults = dict()
    for a in parser._actions:
        defaults[a.dest] = a.default

    if 'help' in defaults:
        del defaults['help']

    return defaults