How to inactivate a strip in Python? After I make a cross effect strip, this new strip is now referenced in:
bpy.context.scene.sequence_editor.active_strip
Then I try to make a new cross fade transition elsewhere by first setting .select as False in all sequences and then selecting two strips and adding the cross effect strip. Now I get the wrong results apparently because of the active strip. How do I inactivate the active strip?
I deselect all strips successfully via:

for s in bpy.data.scenes['Scene'].sequence_editor.sequences_all:
    s.select = False