function list(){
    if [ -d "$BASE_DIR"/"$NOTEBOOK" ]; then
        printf "\nNotes in %s:\n" "$(basename "$NOTEBOOK")"

        NOTES=(
            $(find "$BASE_DIR"/"$NOTEBOOK" -name "*.$EXT" -print0 |\
                sed s:"$BASE_DIR"/"$NOTEBOOK"/: "    " :g |\
                sed -e s:".$EXT"::g | tr "/" " ")
        )
        let i=0
        for NOTE in "${NOTES[@]}"; do
            if [ -d "$BASE_DIR"/"$NOTEBOOK"/"$NOTE" ]; then
                if [ "$LAST_SECTION" != "$NOTE" ]; then
                    printf "  Section: %s\n" "$NOTE"
                fi
                LAST_SECTION="$NOTE"
            else
                #if [ $(($i % 1)) -eq 0 ]; then
                #    printf "\n     "
                #fi
                printf "    %s\n" "$NOTE"
            fi
            let i++
        done
        printf "\n"
    else
        echo ""
        echo "ERROR: Notebook $NOTEBOOK does not exist."
        echo ""
    fi
}