cancellation.rb in concurrent-ruby-edge-0.7.0

- old
+ new

@@ -1,5 +1,7 @@
 require 'concurrent/concern/deprecation'
+require 'concurrent/synchronization/object'
+require 'concurrent/promises'
 
 module Concurrent
 
   # TODO (pitr-ch 27-Mar-2016): cooperation with mutex, condition, select etc?
   # TODO (pitr-ch 10-Dec-2018): integrate with enumerator?