golang-github-fatih-set-dev 0.2.1-1 (s390x binary) in ubuntu groovy

 Set provides both threadsafe and non-threadsafe implementations of a
 generic set data structure. The thread safety encompasses all operations
 on one set. Operations on multiple sets are consistent in that the
 elements of each set used was valid at exactly one point in time between
 the start and the end of the operation. Because it's thread safe, you
 can use it concurrently with your goroutines.