*firstプロパティ
*lastプロパティ
====変換====
=====Array -> Set =====
<pre>
1> let ary: [Int] = [3,2,3,2]
ary: [Int] = 4 values {
[0] = 3
[1] = 2
[2] = 3
[3] = 2
}
2> print(Set(ary))
[3, 2]
</pre>
===== Set -> Array =====
<pre>
6> let set: Set<Int> = [3,4,5,6]
set: Set<Int> = 4 values {
[0] = 4
[1] = 6
[2] = 3
[3] = 5
}
7> print(Array(set))
[4, 6, 3, 5]
</pre>
==クロージャ==