Set is a basic and simple, hash-based, Set data structure implementation in Go.
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.
