[NFC] polish colossalai/builder/builder.py code style (#662)

colossalai/builder/builder.py

@@ -7,6 +7,7 @@ from collections.abc import Iterable
 from colossalai.registry import *
 
 
+
 def build_from_config(module, config: dict):
     """Returns an object of :class:`module` constructed from `config`.
 
@@ -64,6 +65,7 @@ def build_from_registry(config, registry: Registry):
     return obj
 
 
+
 def build_layer(config):
     """Returns a layer object of :class:`nn.Module` constructed from `config`.
 
@@ -243,7 +245,6 @@ def build_lr_scheduler(config, optimizer):
     config_['optimizer'] = optimizer
     return build_from_registry(config_, LR_SCHEDULERS)
 
-
 def build_schedule(config):
     """Returns a schedule of :class:`colossalai.engine.schedule.BaseSchedule`.