Add the state property to Sheet.

[maciejtrybilo]

This adds the possibility to check the state of the worksheet. In particular it allows seeing whether the sheet is hidden or visible.

[Joannis]

In contrast to name, id and relationship - state seems to me more fit to be an enum.

[Joannis]

Also, please (re-)mark me for review so that I see it in my list of open PRs to review when you're ready

[maciejtrybilo]

Sure, I didn't use an enum because I've no idea what are the possible values. I've seen "visible", "hidden", and "veryHidden" XD
I guess people can add if they know about other states.

[Joannis]

If we don't know the exhaustive list of states, let's do a struct similar to this instead:

public struct State: RawRepresentable, Codable {
  public var rawValue: String
  
  public func encode(to encoder: Encoder) throws {
    var container = encoder.singleValueContainer()
    try container.encode(rawValue)
  }
  
  public init(from decoder: Decoder) throws {
    let container = try decoder.singleValueContainer()
    self.rawValue = try container.decode(String.self)
  }
  
  public static let visible = State(rawValue: "visible")
  public static let hidden = State(rawValue: "hidden")
  public static let veryHidden = State(rawValue: "veryHidden")
}

[Joannis]

Please tag me again when you have a reply/updated the code. Sorry about the ping-ponging, but if we don't know the exhaustive list of cases, we cannot use an enum at this stage. Swift doesn't allow libraries to have unknown future cases using @unknown default: