protocol ConnectionServerProtocol {

    func connectWithUsernameAndPassword(username: String, password: String)
}

var username: String?
var password: String?
let connectionServerProtocol: ConnectionServerProtocol

public init(connectionServerProtocol: ConnectionServerProtocol) {
    self.connectionServerProtocol = connectionServerProtocol
}

public func connectWithUsernameAndPassword(username: String, password: String) {

    self.username = username
    self.password = MD5(password)
    self.connectionServerProtocol.dataTask()
}

let cs = ConnectionServer()

let cs = ConnectionServer(connectionServerProtocol:ConnectionServerProtocol)

let cs = ConnectionServer(connectionServerProtocol: ConnectionServerProtocol.self as! ConnectionServerProtocol)

let cs = ConnectionServer.self
cs.connectWithUsernameAndPassword(username: SomeUserName", password:"SomePassword")