[NFC] polish colossalai/nn/lr_scheduler/multistep.py code style (#1572)

colossalai/nn/lr_scheduler/multistep.py

@@ -22,7 +22,13 @@ class MultiStepLR(_MultiStepLR):
             the schedule is started from the beginning or When last_epoch=-1, sets initial lr as lr.
     """
 
-    def __init__(self, optimizer, total_steps: int, milestones: List[int] = None, gamma: float = 0.1, last_epoch: int = -1, **kwargs):
+    def __init__(self,
+                 optimizer,
+                 total_steps: int,
+                 milestones: List[int] = None,
+                 gamma: float = 0.1,
+                 last_epoch: int = -1,
+                 **kwargs):
         super().__init__(optimizer, milestones, gamma=gamma, last_epoch=last_epoch)
 
 
@@ -41,12 +47,16 @@ class MultiStepWarmupLR(WarmupScheduler):
             the schedule is started from the beginning or When last_epoch=-1, sets initial lr as lr.
     """
 
-    def __init__(self, optimizer, total_steps: int, warmup_steps: int = 0, milestones: List[int] = None,
-                 gamma: float = 0.1, last_epoch: int = -1, **kwargs):
+    def __init__(self,
+                 optimizer,
+                 total_steps: int,
+                 warmup_steps: int = 0,
+                 milestones: List[int] = None,
+                 gamma: float = 0.1,
+                 last_epoch: int = -1,
+                 **kwargs):
         if len(milestones) == 0:
             raise ValueError('milestones cannot be empty')
-        milestones = [
-            v - warmup_steps for v in milestones if v >= warmup_steps]
-        base_scheduler = _MultiStepLR(optimizer, milestones=milestones,
-                                      gamma=gamma)
+        milestones = [v - warmup_steps for v in milestones if v >= warmup_steps]
+        base_scheduler = _MultiStepLR(optimizer, milestones=milestones, gamma=gamma)
         super().__init__(optimizer, warmup_steps, base_scheduler, last_epoch=last_epoch)