I am programming in scheme

$($define $($sum n$)$

$($if $($eq$?$ n $0)$

$0$

$(+$ n $($sum $(-$ n $1)))$

$)$

$)$

$($define $($ReverseEm elems$)$

$($if $($null$?$ elems$)$

$\text{'}()$

$($append $($ReverseEm $($cdr elems$))$

$($list $($car elems$)))))$

$($define $($nonNegative num$)$

$($if $(>=$ num $0)$

num

$0)$

$)$

Now want to make a function to use all three of these functions, with a list of numbers, summation the positive numbers, reverse the list.