Fix flake8 error and limit python3 versions

Author: hackermd

.travis.yml

@@ -1,9 +1,8 @@
 language: python
 python:
-  - "2.7"
-  - "3.4"
   - "3.5"
   - "3.6"
+  - "3.7"
 addons:
   apt:
     packages:

setup.py

@@ -29,6 +29,9 @@
         'Topic :: Multimedia :: Graphics',
         'Topic :: Scientific/Engineering :: Information Analysis',
         'Programming Language :: Python :: 3',
+        'Programming Language :: Python :: 3.5',
+        'Programming Language :: Python :: 3.6',
+        'Programming Language :: Python :: 3.7',
         'Development Status :: 4 - Beta',
     ],
     entry_points={

src/dicomweb_client/api.py

@@ -1389,13 +1389,18 @@ def _http_post_multipart_application_dicom(
             'boundary=0f3cf5c0-70e0-41ef-baef-c6f9f65ec3e1'
         )
         content = self._encode_multipart_message(data, content_type)
-        response = self._http_post(
+        self._http_post(
             url,
             content,
             headers={'Content-Type': content_type}
         )
         # FIXME: return information
         # http://dicom.nema.org/medical/dicom/current/output/chtml/part18/chapter_I.html
+        # response = self._http_post(
+        #     url,
+        #     content,
+        #     headers={'Content-Type': content_type}
+        # )
         # response.content
         return {}