add features attr to _info()

arithmetic.py

@@ -118,9 +118,15 @@ class Arithmetic(datasets.GeneratorBasedBuilder):
     ]
 
     def _info(self):
+        features = datasets.Features(
+                {
+                    "context": datasets.Value("string"),
+                    "completion": datasets.Value("string"),
+                }
+            )
         return datasets.DatasetInfo(
             description=f"{_DESCRIPTION}\n{self.config.description}",
-            features=self.config.features,
+            features=features,
             homepage=_HOMEPAGE,
             license=_LICENSE,
             citation=_CITATION,