How can shape keys be driven by an Empty's coordinates relative to the object? I'm guessing this can be done with a Python expression but not sure how to write it.

Also, how might we specify the falloff curve for that Empty's influence?
How can shape keys be driven by an Empty's coordinates relative to the object? I'm guessing this can be done with a Python expression but not sure how to write it.

Also, how might we specify the falloff curve for that Empty's influence?