for https://scratch.mit.edu/discuss/topic/278443/ maps range 1..8 to discontinuous range 1..3, 6..10 uses floor and ceiling creatively! [credit to deck26 for spotting a minor bug]
see inside for block to backpack... key code is (([ceiling v] of (([floor v] of ((((pick random (3) to (10)) * (2)) * (2.1))) / (2))) - (6)) the .1 in 2.1 affects how frequently the gap repeats.
