Unwrapping Optionals in Swift

    private static func flickrURL(endPoint: EndPoint, parameters: [String:String]?) -> URL {
              var components = URLComponents(string: baseURLString)!
              var queryItems = [URLQueryItem]()
              
              if let additionalParams = parameters {
                  for (key, value) in additionalParams{
                      let item = URLQueryItem(name: key, value: value)
                      queryItems.append(item)
                  }
              }
          }