[NFC] polish colossalai/builder/builder.py code style (#1265)

colossalai/builder/builder.py

@@ -6,7 +6,6 @@ import inspect
 from colossalai.registry import *
 
 
-
 def build_from_config(module, config: dict):
     """Returns an object of :class:`module` constructed from `config`.
 
@@ -46,23 +45,20 @@ def build_from_registry(config, registry: Registry):
     Raises:
         Exception: Raises an Exception if an error occurred when building from registry.
     """
-    config_ = config.copy()  # keep the original config untouched
+    config_ = config.copy()    # keep the original config untouched
-    assert isinstance(
+    assert isinstance(registry, Registry), f'Expected type Registry but got {type(registry)}'
-        registry, Registry), f'Expected type Registry but got {type(registry)}'
 
     mod_type = config_.pop('type')
-    assert registry.has(
+    assert registry.has(mod_type), f'{mod_type} is not found in registry {registry.name}'
-        mod_type), f'{mod_type} is not found in registry {registry.name}'
     try:
         obj = registry.get_module(mod_type)(**config_)
     except Exception as e:
-        print(
+        print(f'An error occurred when building {mod_type} from registry {registry.name}', flush=True)
-            f'An error occurred when building {mod_type} from registry {registry.name}',
-            flush=True)
         raise e
 
     return obj
 
+
 def build_gradient_handler(config, model, optimizer):
     """Returns a gradient handler object of :class:`BaseGradientHandler` constructed from `config`,
     `model` and `optimizer`.