Custom jinja2 filters?

[anjiro]

I'm evaluating moving from Pelican to Wok, but I have a number of custom jinja2 filters installed in Pelican that I don't want to lose. Is there a Wok mechanism to install custom filters? As an example, I have the following filter:

def ago(dto, *args):
    """Return the number of seconds ago the passed datetime object
    was."""
    return (datetime.now(pytz.timezone(TIMEZONE)) - dto).total_seconds()

to custom sort some entries.