def instances(doc):
    return doc["doc_type"] == "XFormInstance"
Get an Edge Index or create it if it doesn't exist.
dataset/ETHPy150Open dimagi/commcare-hq/corehq/ex-submodules/couchforms/filters.py/instances--crossover with--dataset/ETHPy150Open espeed/bulbs/bulbs/rexster/index.py/EdgeIndexProxy.get_or_create