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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def _validate_explicit_consumer_groups(cls, val):
 """Validate any explicitly specified consumer groups. While the check does not require specifying consumer groups, if they are specified this method should be used to validate them. val = {'consumer_group': {'topic': [0, 1]}} """

        assert isinstance(val, dict)
        for consumer_group, topics in iteritems(val):
            assert isinstance(consumer_group, string_types)
            # topics are optional
            assert isinstance(topics, dict) or topics is None
            if topics is not None:
                for topic, partitions in iteritems(topics):
                    assert isinstance(topic, string_types)
                    # partitions are optional
                    assert isinstance(partitions, (list, tuple)) or partitions is None
                    if partitions is not None:
                        for partition in partitions:
                            assert isinstance(partition, int)