code: def test_linkpred_neg_sampler(neg_sampler):
      data = "cora"
      node_model = "gcn"
      edge_model = "ele"
      custom_cfg = (
          f"{data}_{node_model}_{edge_model}_{neg_sampler}.yaml"
      )
      if neg_sampler == "":
          os.system(
              "dgl configure linkpred --data {} --node-model {} --edge-model {} --cfg {}".format(
                  data, node_model, edge_model, custom_cfg
              )
          )
      else:
          os.system(
              "dgl configure linkpred --data {} --node-model {} --edge-model {} --neg-sampler {} --cfg {}".format(
                  data, node_model, edge_model, neg_sampler, custom_cfg
              )
          )
      assert os.path.exists(custom_cfg)
  
      custom_script = (
          f"{data}_{node_model}_{edge_model}_{neg_sampler}.py"
      )
      os.system(
          "dgl export --cfg {} --output {}".format(
              custom_cfg, custom_script
          )
      )
      assert os.path.exists(custom_script)
  
file_path: dgl/tests/go/test_pipeline.py
imports: import os
  import pytest
label_desc: Use image node_id 8 for calling a global function with example usage: test_linkpred_neg_sampler(neg_sampler) without return types