$ flutter run --machine
[{"event":"app.start","params":{"appId":"95ec9ce1-98b0-4440-a8b3-d73e36fa8d39","deviceId":"b851637e924ad4a23cb62691cfab9a1251fa7aef","directory":"/Users/tvolkert/project/flutter/flutter/examples/hello_world","supportsRestart":true}}]
Launching lib/main.dart on Boq in debug mode...
Multiple valid development certificates available:
  1) iPhone Developer: Google Development (3F4Y5873JF)
  2) iPhone Developer: Todd Volkert (VEM2GJ2RW9)
  a) Abort
Please select a certificate for code signing [1|2|a]: [{"event":"app.stop","params":{"appId":"95ec9ce1-98b0-4440-a8b3-d73e36fa8d39","error":"Bad state: Stream has already been listened to."}}]