How to make multiple writes in a transaction

Guide to making transactional writes

txn to wrap multiple requests into one transaction:

05_etcdctl_transaction_2016050501

etcdctl --endpoints=$ENDPOINTS put user1 bad
etcdctl --endpoints=$ENDPOINTS txn --interactive

compares:
value("user1") = "bad"

success requests (get, put, delete):
del user1

failure requests (get, put, delete):
put user1 good