def is_subset_of(self, *supersets):
        if not isinstance(self.val, collections.Iterable):
            raise TypeError('val is not iterable')
        if len(supersets) == 0:
            raise ValueError('one or more superset args must be given')

        # flatten supersets
        superset = []
        for j in supersets:
            try:
                for k in j:
                    if k not in superset:
                        superset.append(k)
            except Exception:
                if j not in superset:
                    superset.append(j)

        for i in self.val:
            if i not in superset:
                self._err('Expected <%s> to be subset of %s, but <%s> was missing.' % (self.val, superset, i))

        return self

### dict assertions ###
child.stdout.readline() that also reacts to signals.
dataset/ETHPy150Open ActivisionGameScience/assertpy/assertpy/assertpy.py/AssertionBuilder.is_subset_of--crossover with--dataset/ETHPy150Open mk-fg/pulseaudio-mixer-cli/pa-mixer-mk2.py/PAMixerDBusBridge._child_readline_poll