# Add each item of `coll`.
# var a = [1,2]
- # a.add_all [3..5]
+ # a.add_all([3..5])
# assert a.has(4) == true
# assert a.has(10) == false
fun add_all(coll: Collection[E]) do for i in coll do add(i)
# var x = new HashMap[String, Int]
# x["four"] = 4
# x.clear
- # x.keys.has("four") == false
+ # assert x.keys.has("four") == false
#
# ENSURE `is_empty`
fun clear is abstract