See also Joseki-related life-and-death example 2.
This is another shape often resulting from a 3-3 invasion.
Let's try a few attacks for White.
Black lives, but White can make an endgame gain at a.
Making the L+2 group saves all 6 stones but this time, the other white descent (on top) is sente, as this will threaten a ko.
If white has the marked stone, for example because black threatened to connect an outside group here, the corner can now be killed.
Sandra: If itís black turn, can it be saved?
Sandra: Thank you!