add domain_id, pair_id for flat representation

mfaq.py

@@ -58,7 +58,8 @@ class MFAQ(datasets.GeneratorBasedBuilder):
         if "_flat" in self.config.name: 
             features = datasets.Features(
                 {
-                    "id": datasets.Value("int64"),
+                    "domain_id": datasets.Value("int64"),
+                    "pair_id": datasets.Value("int64"),
                     "language": datasets.Value("string"),
                     "num_pairs": datasets.Value("int64"),
                     "domain": datasets.Value("string"),
@@ -117,7 +118,8 @@ class MFAQ(datasets.GeneratorBasedBuilder):
                     if "flat" in self.config.name:
                         for i, pair in enumerate(data["qa_pairs"]):
                             yield f"{filepath}_{_id}_{i}", {
-                                "id": data["id"],
+                                "domain_id": data["id"],
+                                "pair_id": i,
                                 "domain": data["domain"],
                                 "language": data["language"],
                                 "num_pairs": 1,