diff --git a/abl/bridge/base_bridge.py b/abl/bridge/base_bridge.py
index ba1a663..c9261fb 100644
--- a/abl/bridge/base_bridge.py
+++ b/abl/bridge/base_bridge.py
@@ -5,8 +5,6 @@ from ..learning import ABLModel
 from ..reasoning import Reasoner
 from ..structures import ListData
 
-DataSet = Tuple[List[List[Any]], Optional[List[List[Any]]], List[List[Any]]]
-
 
 class BaseBridge(metaclass=ABCMeta):
     def __init__(self, model: ABLModel, reasoner: Reasoner) -> None:
@@ -24,28 +22,37 @@ class BaseBridge(metaclass=ABCMeta):
 
     @abstractmethod
     def predict(self, data_samples: ListData) -> Tuple[List[List[Any]], List[List[Any]]]:
-        """Placeholder for predict labels from input."""
+        """Placeholder for predicting labels from input."""
 
     @abstractmethod
     def abduce_pseudo_label(self, data_samples: ListData) -> List[List[Any]]:
-        """Placeholder for abduce pseudo labels."""
+        """Placeholder for abducing pseudo labels."""
 
     @abstractmethod
     def idx_to_pseudo_label(self, data_samples: ListData) -> List[List[Any]]:
-        """Placeholder for map label space to symbol space."""
+        """Placeholder for mapping indexes to pseudo labels."""
 
     @abstractmethod
     def pseudo_label_to_idx(self, data_samples: ListData) -> List[List[Any]]:
-        """Placeholder for map symbol space to label space."""
+        """Placeholder for mapping pseudo labels to indexes."""
 
     @abstractmethod
-    def train(self, train_data: Union[ListData, DataSet]):
-        """Placeholder for train loop of ABductive Learning."""
+    def train(
+        self,
+        train_data: Union[ListData, Tuple[List[List[Any]], Optional[List[List[Any]]], List[Any]]],
+    ):
+        """Placeholder for training loop of ABductive Learning."""
 
     @abstractmethod
-    def valid(self, valid_data: Union[ListData, DataSet]) -> None:
+    def valid(
+        self,
+        valid_data: Union[ListData, Tuple[List[List[Any]], Optional[List[List[Any]]], List[Any]]],
+    ) -> None:
         """Placeholder for model test."""
 
     @abstractmethod
-    def test(self, test_data: Union[ListData, DataSet]) -> None:
+    def test(
+        self,
+        test_data: Union[ListData, Tuple[List[List[Any]], Optional[List[List[Any]]], List[Any]]],
+    ) -> None:
         """Placeholder for model validation."""
diff --git a/abl/bridge/simple_bridge.py b/abl/bridge/simple_bridge.py
index 508c106..df4accd 100644
--- a/abl/bridge/simple_bridge.py
+++ b/abl/bridge/simple_bridge.py
@@ -8,7 +8,7 @@ from ..learning import ABLModel
 from ..reasoning import Reasoner
 from ..structures import ListData
 from ..utils import print_log
-from .base_bridge import BaseBridge, DataSet
+from .base_bridge import BaseBridge
 
 
 class SimpleBridge(BaseBridge):
@@ -55,8 +55,10 @@ class SimpleBridge(BaseBridge):
 
     def train(
         self,
-        train_data: Union[ListData, DataSet],
-        val_data: Optional[Union[ListData, DataSet]] = None,
+        train_data: Union[ListData, Tuple[List[List[Any]], Optional[List[List[Any]]], List[Any]]],
+        val_data: Optional[
+            Union[ListData, Tuple[List[List[Any]], Optional[List[List[Any]]], List[Any]]]
+        ] = None,
         loops: int = 50,
         segment_size: Union[int, float] = -1,
         eval_interval: int = 1,
@@ -79,12 +81,12 @@ class SimpleBridge(BaseBridge):
                 self.pseudo_label_to_idx(sub_data_samples)
                 loss = self.model.train(sub_data_samples)
 
-                print_log(
-                    f"loop(train) [{loop + 1}/{loops}] segment(train) \
-                        [{(seg_idx + 1)}/{(len(data_samples) - 1) // segment_size + 1}] \
-                            model loss is {loss:.5f}",
-                    logger="current",
+                log_string = (
+                    f"loop(train) [{loop + 1}/{loops}] segment(train) "
+                    f"[{(seg_idx + 1)}/{(len(data_samples) - 1) // segment_size + 1}] "
+                    f"model loss is {loss:.5f}"
                 )
+                print_log(log_string, logger="current")
 
             if (loop + 1) % eval_interval == 0 or loop == loops - 1:
                 print_log(f"Evaluation start: loop(val) [{loop + 1}]", logger="current")
@@ -114,12 +116,18 @@ class SimpleBridge(BaseBridge):
             msg += k + f": {v:.3f} "
         print_log(msg, logger="current")
 
-    def valid(self, valid_data: Union[ListData, DataSet]) -> None:
+    def valid(
+        self,
+        valid_data: Union[ListData, Tuple[List[List[Any]], Optional[List[List[Any]]], List[Any]]],
+    ) -> None:
         if not isinstance(valid_data, ListData):
             data_samples = self.data_preprocess(*valid_data)
         else:
             data_samples = valid_data
         self._valid(data_samples)
 
-    def test(self, test_data: Union[ListData, DataSet]) -> None:
+    def test(
+        self,
+        test_data: Union[ListData, Tuple[List[List[Any]], Optional[List[List[Any]]], List[Any]]],
+    ) -> None:
         self.valid(test_data)