string :post-val ( string $KEY )
string :post-val ( int $NUM )

When passed an int, returns the value of the NUM-th POST value present.
When passed a string, returns the value associated with the given KEY in POST data.

# POST test.
:writeln s'POST values set: ' :post-num
:set &C i0
!while :lt $C :post-num
    :writeln s'val' $C s': ' (:post-key $C) s'=' :post-val $C
    :add &C i1
    !done