Implementation of a token for shadow with internal methods

DesignSystem.Shadow.swift

public enum Shadow {
  
  case level1
  case level2
  case level3
}

internal extension Shadow {

  var x: CGFloat { ... }
  var y: CGFloat { ... }
  
  var radius: CGFloat { ... }
  var opacity: CGFloat { ... }
  
  #if os(iOS)
  var uiColor: UIColor { ... }
  #endif
  
  #if canImport(SwiftUI)
  @available(iOS 13, *)
  var color: Color { ... }
  #endif
}