Spread Syntax for Swift Arrays (ala es6)

Array+Spread.swift

extension Array {
    static func ... (lhs: [Self.Element], rhs: [Self.Element]) -> [Self.Element] {
        var copy = lhs
        copy.append(contentsOf: rhs)
        return copy
    }

    static func ... (lhs: Self.Element, rhs: [Self.Element]) -> [Self.Element] {
        var copy = [lhs]
        copy.append(contentsOf: rhs)
        return copy
    }

    static func ... (lhs: [Self.Element], rhs: Self.Element) -> [Self.Element] {
        var copy = lhs
        copy.append(rhs)
        return copy
    }
}

let foo: [String] = ["1"]...["2", "3"]
print(foo) // ["1", "2", "3"]

let bar: [String] = "1"...["2", "3"]
print(bar) // ["1", "2", "3"]

let baz: [String] = ["1", "2"]..."2" 

print(baz) // ["1", "2", "2"]