Read-only set interface (subinterface of IMapSource<K,any>).
The word "set" usually means that each item in the collection is unique
(appears only once, based on a definition of equality used by the
collection.) Objects conforming to this interface aren't guaranteed not
to contain duplicates, but as an example, BTree<K,V> implements this
interface and does not allow duplicates.
Read-only set interface (subinterface of IMapSource<K,any>). The word "set" usually means that each item in the collection is unique (appears only once, based on a definition of equality used by the collection.) Objects conforming to this interface aren't guaranteed not to contain duplicates, but as an example, BTree<K,V> implements this interface and does not allow duplicates.