def __add__(self, other):
        if type(self) == type(other):
            result = copy(other)

            result.isreset = self.isreset or other.isreset
            for attribute in self.attributes:
                if attribute not in result.attributes:
                    result.attributes[attribute] = self.attributes[attribute]
            if not result.fg:
                result.fg = self.fg
            if not result.bg:
                result.bg = self.bg
            return result
        else:
            return other.__class__(self) + other
Error checking on routines that should not return 0.
dataset/ETHPy150Open tomerfiliba/plumbum/plumbum/colorlib/styles.py/Style.__add__--crossover with--dataset/ETHPy150Open dcramer/django-compositepks/django/contrib/gis/geos/prototypes/errcheck.py/check_zero