Fix/format colossalai/engine/paramhooks/(#350)

colossalai/engine/paramhooks/__init__.py

 from ._param_hookmgr import BaseParamHookMgr
+
 __all__ = ["BaseParamHookMgr"]

colossalai/engine/paramhooks/_param_hookmgr.py

@@ -2,7 +2,9 @@ from typing import Callable, List
 import torch
 import functools
 
+
 class BaseParamHookMgr(object):
+
     def __init__(self, param_list: List[torch.nn.Parameter]) -> None:
         r"""
         register backward hook on every parameters of module
@@ -10,7 +12,7 @@ class BaseParamHookMgr(object):
         self._param_list = param_list
         self._hook_list = []
 
-    def register_backward_hooks(self, hook_call : Callable) -> None:
+    def register_backward_hooks(self, hook_call: Callable) -> None:
         r"""
         The hook_call will be called every time a gradient with respect to the a param in self.param_list
         is computed.