public static string Join(ReadOnlySpan <char> path1, ReadOnlySpan <char> path2)
 {
     if (path1.Length == 0)
     {
         return(path2.ToString());
     }
     return(path2.Length == 0 ? path1.ToString() : Path.JoinInternal(path1, path2));
 }
 public static string Join(
     ReadOnlySpan <char> path1,
     ReadOnlySpan <char> path2,
     ReadOnlySpan <char> path3)
 {
     if (path1.Length == 0)
     {
         return(Path.Join(path2, path3));
     }
     if (path2.Length == 0)
     {
         return(Path.Join(path1, path3));
     }
     return(path3.Length == 0 ? Path.Join(path1, path2) : Path.JoinInternal(path1, path2, path3));
 }