human
Solve the following python programming problem given the following code:
@register.tag(u'trans')
def do_translate(parser, token):
assistant
#Here is the Python code you requested.

    """This will mark a string for translation and will
    translate the string for the current language.
    Usage::
    {% trans "this is a test" %}
    This will mark the string for translation so it will
    be pulled out by mark-messages.py into the .po files
    and will run the string through the translation engine.
    There is a second form::
    {% trans "this is a test" noop %}
    This will only mark for translation, but will return
    the string unchanged. Use it when you need to store
    values into forms that should be translated later on.
    You can use variables instead of constant strings
    to translate stuff you marked somewhere else::
    {% trans variable %}
    This will just try to translate the contents of
    the variable ``variable``. Make sure that the string
    in there is something that is in the .po file.
    It is possible to store the translated string into a variable::
    {% trans "this is a test" as var %}
    {{ var }}
    Contextual translations are also supported::
    {% trans "this is a test" context "greeting" %}
    This is equivalent to calling pgettext instead of (u)gettext.
    """
    class TranslateParser(TokenParser, ):
        def top(self):
            value = self.value()
            if (value[0] == u"'"):
                m = re.match(u"^'([^']+)'(\\|.*$)", value)
                if m:
                    value = (u'"%s"%s' % (m.group(1).replace(u'"', u'\\"'), m.group(2)))
                elif (value[(-1)] == u"'"):
                    value = (u'"%s"' % value[1:(-1)].replace(u'"', u'\\"'))
            noop = False
            asvar = None
            message_context = None
            while self.more():
                tag = self.tag()
                if (tag == u'noop'):
                    noop = True
                elif (tag == u'context'):
                    message_context = parser.compile_filter(self.value())
                elif (tag == u'as'):
                    asvar = self.tag()
                else:
                    raise TemplateSyntaxError(u'Only    options    for    \'trans\'    are    \'noop\',    \'context    "xxx"\',    and    \'as    VAR\'.')
            return (value, noop, asvar, message_context)
    (value, noop, asvar, message_context) = TranslateParser(token.contents).top()
    return TranslateNode(parser.compile_filter(value), noop, asvar, message_context)