Cannot find the ens.nameByHash() function code.

[wangkm]

In ens-subgraph/src/ensRegistry.ts, line 97, I found this:
let label = ens.nameByHash(event.params.label.toHexString())
There's only an empty declaration in graph-ts lib for this function.
Could anybody tell me where can I found the implementation code?
Thanks.

[Pana]

This code is implemented in graph-node