// abcdefg -> abcd
let from = ABCName.index(ABCName.startIndex, offsetBy:0)
let to = ABCName.index(ABCName.startIndex, offsetBy:4)
let newString = String(ABCName[from..<to])
// abcdefg -> defg
let from = ABCName.index(ABCName.startIndex, offsetBy:3)
let to = ABCName.index(ABCName.startIndex, offsetBy:ABCName.count)
let newString = String(ABCName[from..<to])
