on-add hook to add default priority to taskwarrior tasks if not specified

defprio.py

#!/usr/bin/env python

import sys
import json

DEF_PRIO = 'M'
added_task = json.loads(sys.stdin.readline())
if 'priority' not in added_task:
    sys.stderr.write("Adding default priority: {}\n".format(DEF_PRIO))
    added_task['priority'] = DEF_PRIO
    
#  see https://taskwarrior.org/docs/hooks_guide.html
# save as .task/hooks/on-add
print(json.dumps(added_task))
sys.exit(0)