add docstrings, refactor logger

Former-commit-id: c34e489d71f8f539028543ccf8ee92cecedd6276

src/llamafactory/train/trainer_utils.py

@@ -26,6 +26,7 @@ from transformers.modeling_utils import is_fsdp_enabled
 from transformers.optimization import get_scheduler
 from transformers.pytorch_utils import ALL_LAYERNORM_LAYERS
 from transformers.trainer_pt_utils import get_parameter_names
+from typing_extensions import override
 
 from ..extras.constants import IGNORE_INDEX
 from ..extras.logging import get_logger
@@ -60,9 +61,11 @@ class DummyOptimizer(torch.optim.Optimizer):
         self.optimizer_dict = optimizer_dict
         super().__init__([dummy_tensor], {"lr": lr})
 
+    @override
     def zero_grad(self, set_to_none: bool = True) -> None:
         pass
 
+    @override
     def step(self, closure: Optional[Callable[[], float]] = None) -> Optional[float]:
         pass