diff -ur v16/blk.py v17/blk.py
--- v16/blk.py	2018-08-31 22:53:08.000000000 +0900
+++ v17/blk.py	2018-09-11 22:36:57.000000000 +0900
@@ -3,9 +3,11 @@
 import sys
 import yaml
 
+flow = '-f' in sys.argv
+
 s = sys.stdin.read()
 o = yaml.load(s)
-s = yaml.dump(o, default_flow_style=False)
+s = yaml.dump(o, default_flow_style=flow)
 sys.stdout.write(s)
 
 # EOF