line-mode
"0"
catenate #(list+list)
pop-a
( "hkl" )
m:
    itemize
    tuck-a
    split
    head
    dup
    1
    left-cons
    last
    odd
        "1"
        catenate #(list+list)
    f2
    read-nums
    last
}
unwords