How to use the stacker.actions.diff.DictValue function in stacker

def summarize_params_diff(params_diff):
    summary = ''

    added_summary = [v.key for v in params_diff
                     if v.status() is DictValue.ADDED]
    if added_summary:
        summary += 'Parameters Added: %s\n' % ', '.join(added_summary)

    removed_summary = [v.key for v in params_diff
                       if v.status() is DictValue.REMOVED]
    if removed_summary:
        summary += 'Parameters Removed: %s\n' % ', '.join(removed_summary)

    modified_summary = [v.key for v in params_diff
                        if v.status() is DictValue.MODIFIED]
    if modified_summary:
        summary += 'Parameters Modified: %s\n' % ', '.join(modified_summary)

    return summary

added_set = new_set - old_set
    removed_set = old_set - new_set
    common_set = old_set & new_set

    changes = 0
    output = []
    for key in added_set:
        changes += 1
        output.append(DictValue(key, None, new_dict[key]))

    for key in removed_set:
        changes += 1
        output.append(DictValue(key, old_dict[key], None))

    for key in common_set:
        output.append(DictValue(key, old_dict[key], new_dict[key]))
        if str(old_dict[key]) != str(new_dict[key]):
            changes += 1

    output.sort(key=attrgetter("key"))
    return [changes, output]

def summarize_params_diff(params_diff):
    summary = ''

    added_summary = [v.key for v in params_diff
                     if v.status() is DictValue.ADDED]
    if added_summary:
        summary += 'Parameters Added: %s\n' % ', '.join(added_summary)

    removed_summary = [v.key for v in params_diff
                       if v.status() is DictValue.REMOVED]
    if removed_summary:
        summary += 'Parameters Removed: %s\n' % ', '.join(removed_summary)

    modified_summary = [v.key for v in params_diff
                        if v.status() is DictValue.MODIFIED]
    if modified_summary:
        summary += 'Parameters Modified: %s\n' % ', '.join(modified_summary)

    return summary

int: number of changed records
        list: [DictValue]
    """

    old_set = set(old_dict)
    new_set = set(new_dict)

    added_set = new_set - old_set
    removed_set = old_set - new_set
    common_set = old_set & new_set

    changes = 0
    output = []
    for key in added_set:
        changes += 1
        output.append(DictValue(key, None, new_dict[key]))

    for key in removed_set:
        changes += 1
        output.append(DictValue(key, old_dict[key], None))

    for key in common_set:
        output.append(DictValue(key, old_dict[key], new_dict[key]))
        if str(old_dict[key]) != str(new_dict[key]):
            changes += 1

    output.sort(key=attrgetter("key"))
    return [changes, output]

old_set = set(old_dict)
    new_set = set(new_dict)

    added_set = new_set - old_set
    removed_set = old_set - new_set
    common_set = old_set & new_set

    changes = 0
    output = []
    for key in added_set:
        changes += 1
        output.append(DictValue(key, None, new_dict[key]))

    for key in removed_set:
        changes += 1
        output.append(DictValue(key, old_dict[key], None))

    for key in common_set:
        output.append(DictValue(key, old_dict[key], new_dict[key]))
        if str(old_dict[key]) != str(new_dict[key]):
            changes += 1

    output.sort(key=attrgetter("key"))
    return [changes, output]