@tornado.gen.coroutine
    def perform(self, ctx, propname, gentext):
        ctx.accum_append('[Unimplemented GenNodeClass: %s]' % (repr(self),))
Helper function that returns the database column for the given field.
dataset/ETHPy150Open erkyrath/tworld/lib/twcommon/gentext.py/GenNodeClass.perform--crossover with--dataset/ETHPy150Open django/django/django/contrib/gis/db/models/query.py/GeoQuerySet._field_column