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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 collect_all_bucket_keys(self):
 """ Just collects all buckets keys from subtree """

        if len(self.childs) == 0:
            # This is a leaf so just return the bucket key (we reached the bucket leaf)
            #print 'Returning (collect) leaf bucket key %s with %d vectors' % (self.bucket_key, self.vector_count)
            return [self.bucket_key]

        # Not leaf, return results of childs
        result = []
        for child in self.childs.values():
            result = result + child.collect_all_bucket_keys()

        return result