I am studying a code that uses guid data types using a ? , and sincerily I don't have idea about what means. ¿Can anybody helpme? Thanks in advance.
public Stream GetContent(Guid fileId, Guid? versionId = null)
{
const string test = "Testing 1-2-3";
// convert string to stream
var byteArray = Encoding.ASCII.GetBytes(test);
var stream = new MemoryStream(byteArray);
return stream;
}