def clean_abstract(abstract, remove_tags=['xref', 'ext-link', 'inline-formula', 'mml:*']):
    """
    Remove unwanted tags from abstract string,
    parsing it as HTML, then only keep the body paragraph contents
    """
    if remove_tags:
        for tag_name in remove_tags:
            abstract = utils.remove_tag(tag_name, abstract)
    return abstract