def _errors(self):
        return self.form.errors.get(self.name, ErrorList())
Matches current tours with attributes of previous tours for the same
dataset/ETHPy150Open AppScale/appscale/AppServer/lib/django-0.96/django/newforms/forms.py/BoundField._errors--crossover with--dataset/ETHPy150Open UDST/activitysim/activitysim/defaults/models/util/vectorize_tour_scheduling.py/get_previous_tour_by_tourid