def default_changelog_generator(item):
    """
    Contruct the default changelog line for a given item (PR).
    """
    title = item['title']
    breaks_compat = 'compatibility' in item['labels']
    pr_url = item['html_url']

    if breaks_compat:
        compat_msg = "**WARNING: Breaks compatibility with previous version.**"
    else:
        compat_msg = ""

    return f" - {title}. {compat_msg} [View pull request]({pr_url})"