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Answer-31C-6
Answer to Question 31C-6
prefix
([ ],
n
)
=
[ ]
prefix
(
L
, 0)
=
[ ]
prefix
(
L
,
n
)
=
head
(
L
)
:
prefix
(
tail
(
L
),
n
−1)
(when
n
> 0 and L ≠ [ ])