def filter_arglist(args, defaults, bound_argnames):
    """
    Filters a list of function argument nodes (``ast.arg``)
    and corresponding defaults to exclude all arguments with the names
    present in ``bound_arguments``.
    Returns a pair of new arguments and defaults.
    """
    new_args = []
    new_defaults = []
    required_args = len(args) - len(defaults)
    for i, arg in enumerate(args):
        if arg.arg not in bound_argnames:
            new_args.append(arg)
            if i >= required_args:
                new_defaults.append(defaults[i - required_args])

    return new_args, new_defaults