Update ace.py

ace.py

@@ -41,7 +41,7 @@ class MockupDataset(datasets.GeneratorBasedBuilder):
     VERSION = datasets.Version("0.0.0")
     BUILDER_CONFIGS = []
     
-    def __init__(self, name=None, data_config={}, **kwargs):
+    def __init__(self, name=None, data_config=None, **kwargs):
         super().__init__(**kwargs)
 
         print(data_config)