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Question
how come this is not working
GDScript is whitespace-sensitive. Your code has two levels of indentation where only one is expected.
Make sure to paste scripts instead of screen shots.
body doesn’t exist in that function, you probably meant to connect to the body_entered signal instead of area_entered
within the if block var y_delta is declared, which only exists within the if block, so un-indenting makes it inaccessable.
You may want to understand scope levels in programming.