Code fails with error: "protocol 'ViewModel' can only be used as a generic constraint because it has Self or associated type requirements"

protocol-associated-types-properties

import Foundation

protocol ViewModel {
    typealias ModelType
    var data: ModelType { get }
}

struct ViewContainer {
    
    var viewModels: [ViewModel]
    
    init() {
        viewModels = [ViewModel]()
    }
    
    mutating func add(model: ViewModel) {
        viewModels.append(model)
    }
}