It is not satisfactory that we cannot reduce the empty list
We remedy the problem by passing an extra parameter to the reduction functions
We call this variant of the reduction functions for accumulation
(accumulate-right - 0 '())
0
(accumulate-right - 0 '(1 2 3 4 5))
3
(accumulate-right append '() (list (list 1 2 3) (list 'a 'b 'c)))
(1 2 3 a b c)
