class RepresentationMixin(object):
    @property
    def react_representation(self):
        raise NotImplementedError(
            'Missing property react_representation in class'
        )

class RepresentationMixin(object):
    def to_react_representation(self, context=None):
        raise NotImplementedError(
            'Missing property to_react_representation in class'
        )

Switch NotImplementedError to to_react_represetnation in mixin
Switch NotImplementedError to to_react_represetnation in mixin
