# assert [1..1[.is_empty == true
fun is_empty: Bool do return length == 0
+ # Alias for `not is_empty`.
+ #
+ # Some people prefer to have conditions grammatically easier to read.
+ #
+ # assert [1,2,3].not_empty == true
+ # assert [1..1[.not_empty == false
+ fun not_empty: Bool do return not self.is_empty
+
# Number of items in the collection.
#
# assert [10,20,30].length == 3