'Append a sequence of (field, model, value) triples to the internal list
that will be used to generate the UPDATE query. Might be more usefully
called add_update_targets() to hint at the extra information here.'

def add_update_fields(self, values_seq):

    for (field, model, val) in values_seq:
        if hasattr(val, 'resolve_expression'):
            val = val.resolve_expression(self, allow_joins=False, for_save=True)
        self.values.append((field, model, val))
