Soft assert for whether the is an instance of cls

        :params obj: the object instance
        :params cls: the class to compare against
        :params msg: (Optional) msg explaining the difference

def verify_is_instance(self, obj, cls, msg=""):
        """
        Soft assert for whether the is an instance of cls

        :params obj: the object instance
        :params cls: the class to compare against
        :params msg: (Optional) msg explaining the difference
        """
        try:
            self.assert_is_instance(obj, cls, msg)
        except AssertionError, e:
            if msg:
                m = "%s:\n%s" % (msg, str(e))
            else:
                m = str(e)
            self.verification_erorrs.append(m)