fix pep8

Author: ignacio

deepaas/api/v2/train.py

@@ -15,7 +15,7 @@
 # under the License.
 
 import asyncio
-import datetime
+from datetime import datetime
 import uuid
 
 from aiohttp import web
@@ -64,10 +64,11 @@ def build_train_response(uuid, training):
                 else:
                     ret["status"] = "done"
                     ret["result"] = training["task"].result()
-                    ret["result"]["duration"] = str(datetime.datetime.strptime(ret["result"]["finish_date"],
-                                                                               '%Y-%m-%d %H:%M:%S.%f')
-                                                    - datetime.datetime.strptime(ret["date"],
-                                                                                 '%Y-%m-%d %H:%M:%S.%f'))
+                    end = datetime.strptime(ret["result"]["finish_date"],
+                                            '%Y-%m-%d %H:%M:%S.%f')
+                    start = datetime.strptime(ret["date"],
+                                              '%Y-%m-%d %H:%M:%S.%f')
+                    ret["result"]["duration"] = str(end - start)
             else:
                 ret["status"] = "running"
             return ret
@@ -82,7 +83,7 @@ async def post(self, request, args, wsk_args=None):
             uuid_ = uuid.uuid4().hex
             train_task = self.model_obj.train(**args)
             self._trainings[uuid_] = {
-                "date": str(datetime.datetime.now()),
+                "date": str(datetime.now()),
                 "task": train_task,
                 "args": args,
             }