@register.filter(needs_autoescape=True)
def highlight(text, sterm, autoescape=None):
    if autoescape:
        esc = conditional_escape
    else:
        esc = lambda x: x
    pattern = re.compile('(%s)' % esc(sterm), re.IGNORECASE)
    result = pattern.sub(r'<strong class="yellow">\1</strong>',text)
    return mark_safe(result)