'module' object has no attribute 'util'

django version 1.8.1

mongoforms/forms.py in MongoForm, line 57

def __init__(self, data=None, files=None, auto_id='id_%s', prefix=None,
        initial=None, error_class=forms.util.ErrorList, label_suffix=':',
        empty_permitted=False, instance=None):

forms.utils.ErrorList