保留内容中的特定标签

def strip_tags(string, allowed_tags=''):
    if allowed_tags != '':
        # Get a list of all allowed tag names.
        allowed_tags = allowed_tags.split(',')
        allowed_tags_pattern = ['</?' + allowed_tag + '[^>]*>' for allowed_tag in allowed_tags]
        all_tags = re.findall(r'<[^>]+>', string, re.I)
        not_allowed_tags = []
        tmp = 0
        for tag in all_tags:
            for pattern in allowed_tags_pattern:
                rs = re.match(pattern, tag)
                if rs:
                    tmp += 1
                else:
                    tmp += 0
            if not tmp:
                not_allowed_tags.append(tag)
            tmp = 0
        for not_allowed_tag in not_allowed_tags:
            string = re.sub(re.escape(not_allowed_tag), '', string)
    else:
        # If no allowed tags, remove all.
        string = re.sub(r'<[^>]*?>', '', string)

    return string


content = strip_tags(content, allowed_tags='br,img,hr,a')
print(content)