from eliot import start_action, to_file
to_file(open("mylog.log", "w"))
with start_action(action_type="login", username="admin"):
try:
# Perform login operation
# ...
# Log successful login
start_action(action_type="login.success").finish()
except Exception as e:
# Log login failure
start_action(action_type="login.failure", reason=str(e)).finish()