code: def _generate(self, g, eids, canonical_etype):
      raise NotImplementedError
  
file_path: dgl/python/dgl/dataloading/negative_sampler.py
imports: from collections.abc import Mapping
  from ..None import backend
label_desc: Use image node_id 1 for calling the _BaseNegativeSampler obj's underlying member method code with example usage: obj._generate(g, eids, canonical_etype) without return types