diff --git a/scripts/hiddenapi/merge_csv.py b/scripts/hiddenapi/merge_csv.py
index a65326c..c17ec25 100755
--- a/scripts/hiddenapi/merge_csv.py
+++ b/scripts/hiddenapi/merge_csv.py
@@ -13,8 +13,7 @@
 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 # See the License for the specific language governing permissions and
 # limitations under the License.
-"""
-Merge multiple CSV files, possibly with different columns.
+"""Merge multiple CSV files, possibly with different columns.
 """
 
 import argparse
@@ -26,34 +25,52 @@
 
 from zipfile import ZipFile
 
-args_parser = argparse.ArgumentParser(description='Merge given CSV files into a single one.')
-args_parser.add_argument('--header', help='Comma separated field names; '
-                                          'if missing determines the header from input files.')
-args_parser.add_argument('--zip_input', help='Treat files as ZIP archives containing CSV files to merge.',
-                         action="store_true")
-args_parser.add_argument('--key_field', help='The name of the field by which the rows should be sorted. '
-                                             'Must be in the field names. '
-                                             'Will be the first field in the output. '
-                                             'All input files must be sorted by that field.')
-args_parser.add_argument('--output', help='Output file for merged CSV.',
-                         default='-', type=argparse.FileType('w'))
+args_parser = argparse.ArgumentParser(
+    description='Merge given CSV files into a single one.'
+)
+args_parser.add_argument(
+    '--header',
+    help='Comma separated field names; '
+    'if missing determines the header from input files.',
+)
+args_parser.add_argument(
+    '--zip_input',
+    help='Treat files as ZIP archives containing CSV files to merge.',
+    action="store_true",
+)
+args_parser.add_argument(
+    '--key_field',
+    help='The name of the field by which the rows should be sorted. '
+    'Must be in the field names. '
+    'Will be the first field in the output. '
+    'All input files must be sorted by that field.',
+)
+args_parser.add_argument(
+    '--output',
+    help='Output file for merged CSV.',
+    default='-',
+    type=argparse.FileType('w'),
+)
 args_parser.add_argument('files', nargs=argparse.REMAINDER)
 args = args_parser.parse_args()
 
 
-def dict_reader(input):
-    return csv.DictReader(input, delimiter=',', quotechar='|')
+def dict_reader(csvfile):
+    return csv.DictReader(csvfile, delimiter=',', quotechar='|')
+
 
 csv_readers = []
-if not(args.zip_input):
+if not args.zip_input:
     for file in args.files:
         csv_readers.append(dict_reader(open(file, 'r')))
 else:
     for file in args.files:
-        with ZipFile(file) as zip:
-            for entry in zip.namelist():
+        with ZipFile(file) as zipfile:
+            for entry in zipfile.namelist():
                 if entry.endswith('.uau'):
-                    csv_readers.append(dict_reader(io.TextIOWrapper(zip.open(entry, 'r'))))
+                    csv_readers.append(
+                        dict_reader(io.TextIOWrapper(zipfile.open(entry, 'r')))
+                    )
 
 if args.header:
     fieldnames = args.header.split(',')
@@ -73,8 +90,8 @@
     keyField = args.key_field
     if keyField:
         assert keyField in fieldnames, (
-            "--key_field {} not found, must be one of {}\n").format(
-            keyField, ",".join(fieldnames))
+            "--key_field {} not found, must be one of {}\n"
+        ).format(keyField, ",".join(fieldnames))
         # Make the key field the first field in the output
         keyFieldIndex = fieldnames.index(args.key_field)
         fieldnames.insert(0, fieldnames.pop(keyFieldIndex))
@@ -83,11 +100,17 @@
         all_rows = heapq.merge(*csv_readers, key=operator.itemgetter(keyField))
 
 # Write all rows from the input files to the output:
-writer = csv.DictWriter(args.output, delimiter=',', quotechar='|', quoting=csv.QUOTE_MINIMAL,
-                        dialect='unix', fieldnames=fieldnames)
+writer = csv.DictWriter(
+    args.output,
+    delimiter=',',
+    quotechar='|',
+    quoting=csv.QUOTE_MINIMAL,
+    dialect='unix',
+    fieldnames=fieldnames,
+)
 writer.writeheader()
 
 # Read all the rows from the input and write them to the output in the correct
 # order:
 for row in all_rows:
-  writer.writerow(row)
+    writer.writerow(row)