a.swift

enum To {
    case anchor(Anchor)
    case size
    case none
  }
class Pin {
  let attribute: Attribute
  var constant: CGFloa
  init(_ attribute:  Attribute, constant: CGFloat = 0) {
    self.attribute = attribute
    self.constant = constant
  }
let item: AnyObject
// key: attribute
// value: constant
var pins: [Pin] = [
var multiplierValue: CGFloat = 1
var priorityValue: Float?
var identifierValue: String?
var referenceBlock: (([NSLayoutConstraint]) -> Void)?
var relationValue: Relation = .equal
var toValue: To = .none