var a: SplayDict<Int, Double> = SplayDict() // make a empty splay set.
var b = SplayDict([1, 3, 2]) // make a set which contains 1, 2, 3.

// and more constructor is building...

var a: SplayDict<Int, Int> = SplayDict()
a.insert(key: 3, value: 7)
// Insert [3 : 7] into SplayDict.
a[5] = 12
// Insert [5 : 12] into SplayDict.

// If you want to insert key which is already exists,
// then being value is replaced with newValue.

_ = a.top 
// Return a top element of SplayDict.
// It's a latest searched data.
// Read-only property

var a: SplayDict<Int, String> = SplayDict()
let value: String? = a.find(key: 7) 
// Return value if search value exists, else return nil.
// And this make searched key(or nearest key) be on a top of SplayDict.

a.delete(key: 5)
// Delete element corresponded with key in SplayDict.
// Make a biggest key under input be a top element.

var a: SplayDict<Int, Double> = SplayDict()
let value: Double? = a.indexOf(3)
// Return n-th value if SplayDict.
// If index is out of range, returns nil.

a.reverse(from: 3, to: 6)
// Reverse elements. (from 3 to 6)
// Implement using Lazy Propagtion.

// example
// Let splay set consists of [0, 1, 2, 3, 4, 5, 6].
// reverse(from: 3, to : 6).
// The result is [0, 1, 2, 6, 5, 4, 3].