/// <summary>
/// Returns a handle in the same directory with the same stem, but with the given extension. If not found, returns <see langword="null"/>.
/// </summary>
/// <param name="this"></param>
/// <param name="extension">The extension, which should NOT have a leading '.', of the handle to retrieve</param>
public static IChildHandle?WithExtension(this IChildHandle @this, string extension)
{
return(@this.WithName($"{@this.GetStem()}.{extension}"));
}
/// <summary>
/// Returns a handle in the same directory with the same extension, but with the given stem. If not found, returns <see langword="null"/>.
/// </summary>
/// <param name="this"></param>
/// <param name="stem">The stem of the handle to retrieve</param>
public static IChildHandle?WithStem(this IChildHandle @this, string stem)
{
return(@this.WithName($"{stem}.{@this.GetExtension()}"));
}