'Returns the entry associated with the given data_usage_key.
Raises:
BlockStructureNotFound if an entry for data_usage_key is not found.'

@classmethod
def get(cls, data_usage_key):

    try:
        return cls.objects.get(data_usage_key=data_usage_key)
    except cls.DoesNotExist:
        log.info(u'BlockStructure:    Not    found    in    table;    %s.', data_usage_key)
        raise BlockStructureNotFound(data_usage_key)
