HeaderViewModel.swift

class HeaderViewModel {
    init(
      title: String, 
      leftButtonTitle: String? = nil, 
      leftButtonAction: (() -> ())? = nil, 
      sizeControlCallback: Binding<Int>? = nil, 
      sizeIndicator: String? = nil, 
      colorIndicator: UIColor? = nil, 
      tiltIndicator: String? = nil) {
        // Assignments removed here for brevity 
    }

    var title: String
    var leftButtonTitle: String? = nil
    var leftButtonAction: (() -> ())? = nil
    var sizeControlCallback: Binding<Int>? = nil
    var sizeIndicator: String? = nil
    var colorIndicator: UIColor? = nil
    var tiltIndicator: String? = nil
}