[NFC] polish colossalai/nn/_ops/addmm.py code style (#3274)

colossalai/nn/_ops/addmm.py

 import torch
+
+from colossalai.tensor import ColoTensor, ColoTensorSpec, ComputePattern, ComputeSpec, ReplicaSpec, ShardSpec, distspec
 from colossalai.tensor.op_wrapper import colo_op_impl
-from colossalai.tensor import ComputePattern, ComputePattern, ComputeSpec, ColoTensor
-from colossalai.tensor import distspec, ColoTensorSpec, ShardSpec, ReplicaSpec
-from ._utils import GeneralTensor, Number, convert_to_colo_tensor
-from ._utils import reduce_input, reduce_grad
+
+from ._utils import GeneralTensor, Number, convert_to_colo_tensor, reduce_grad, reduce_input
 
 
 def colo_addmm_1Drow(input_tensor: ColoTensor, mat1: ColoTensor, mat2: ColoTensor, beta: Number,
@@ -69,9 +69,13 @@ def colo_addmm(input_tensor: GeneralTensor,
     if not mat2.has_compute_spec():    # No Model Parallel Applied
         assert mat2.is_replicate(), 'Invalid mat2 spec for native addmm op'
         assert input_tensor.is_replicate(), 'Invalid input spec for native addmm op'
-        ret_tensor = ColoTensor.from_torch_tensor(
-            tensor=torch.addmm(input_tensor, mat1, mat2, beta=beta, alpha=alpha, **kargs),
-            spec=ColoTensorSpec(mat2.get_process_group()))
+        ret_tensor = ColoTensor.from_torch_tensor(tensor=torch.addmm(input_tensor,
+                                                                     mat1,
+                                                                     mat2,
+                                                                     beta=beta,
+                                                                     alpha=alpha,
+                                                                     **kargs),
+                                                  spec=ColoTensorSpec(mat2.get_process_group()))
     elif mat2.has_compute_pattern(ComputePattern.TP1D):    # Single Model Parallel Applied
         if mat2.is_shard_1drow() and input_tensor.is_replicate():
             mode = 'row'