@register.tag
def querystring(parser, token):
    bits = token.split_contents()
    tag = bits.pop(0)
    updates = token_kwargs(bits, parser)
    # ``bits`` should now be empty of a=b pairs, it should either be empty, or
    # have ``without`` arguments.
    if bits and bits.pop(0) != "without":
        raise TemplateSyntaxError("Malformed arguments to '%s'" % tag)
    removals = [parser.compile_filter(bit) for bit in bits]
    return QuerystringNode(updates, removals)
Given the step, returns a Form prefix to use.
dataset/ETHPy150Open bradleyayers/django-tables2/django_tables2/templatetags/django_tables2.py/querystring--crossover with--dataset/ETHPy150Open AppScale/appscale/AppServer/lib/django-1.4/django/contrib/formtools/wizard/legacy.py/FormWizard.prefix_for_step