merge-chunks: run black formatter

No manual changes and no behavior changes in this commit - simple code
style update from black.

pcap/merge-chunks.py

@@ -9,27 +9,39 @@ import sys
 def positive_int(val):
     i = int(val)
     if i <= 0:
-        raise ValueError('must be greater than 0')
+        raise ValueError("must be greater than 0")
     return i
 
 
 def readable_directory(path):
     po = Path(path)
     if not po.is_dir():
-        raise ValueError('must be path to directory')
+        raise ValueError("must be path to directory")
     return po
 
 
 def main():
     parser = argparse.ArgumentParser(
-        description="Merge subset of PCAP chunks on the fly and write result to stdout")
-
-    parser.add_argument('nchunks', type=positive_int,
-                        help='Number of chunks to randomly select from source_dirs and merge')
-    parser.add_argument('source_dirs', nargs='+', type=readable_directory,
-                        help='Paths to directories with PCAP chunks')
-    parser.add_argument('--seed', default=0, type=int,
-                        help='Randomization seed (default: 0); use negative value to turn off randomization')
+        description="Merge subset of PCAP chunks on the fly and write result to stdout"
+    )
+
+    parser.add_argument(
+        "nchunks",
+        type=positive_int,
+        help="Number of chunks to randomly select from source_dirs and merge",
+    )
+    parser.add_argument(
+        "source_dirs",
+        nargs="+",
+        type=readable_directory,
+        help="Paths to directories with PCAP chunks",
+    )
+    parser.add_argument(
+        "--seed",
+        default=0,
+        type=int,
+        help="Randomization seed (default: 0); use negative value to turn off randomization",
+    )
     args = parser.parse_args()
 
     # reproducible pseudorandomness
@@ -38,24 +50,26 @@ def main():
     pcaps = []
     for dir_path in args.source_dirs:
         pcaps.extend(
-            str(path) for path in dir_path.glob('**/*')
-            if path.is_file() or path.is_fifo())
+            str(path)
+            for path in dir_path.glob("**/*")
+            if path.is_file() or path.is_fifo()
+        )
 
     if args.nchunks > len(pcaps):
-        sys.exit(f'{args.nchunks} chunks requested but only {len(pcaps)} available')
+        sys.exit(f"{args.nchunks} chunks requested but only {len(pcaps)} available")
 
     pcaps.sort()
     if args.seed >= 0:
         random.shuffle(pcaps)
-    mergecap_args = ['mergecap', '-F', 'pcap', '-w', '-']
-    mergecap_args.extend(pcaps[:args.nchunks])
+    mergecap_args = ["mergecap", "-F", "pcap", "-w", "-"]
+    mergecap_args.extend(pcaps[: args.nchunks])
 
-    sys.stderr.write(f'merging {args.nchunks} chunks into PCAP stream on stdout\n')
-    sys.stderr.write(f'executing merge command: {mergecap_args}\n')
+    sys.stderr.write(f"merging {args.nchunks} chunks into PCAP stream on stdout\n")
+    sys.stderr.write(f"executing merge command: {mergecap_args}\n")
     sys.stderr.flush()
 
-    os.execvp('mergecap', mergecap_args)
+    os.execvp("mergecap", mergecap_args)
 
 
-if __name__ == '__main__':
+if __name__ == "__main__":
     main()