verbose outputs for detecting indexes

            echo " either give no index1 file, or give index1 file for each and every read1 file"

            exit 1

        else

            if [[ $verbose ]] then

                echo " No index files given. Automatically detecing from R1 and R2 file names..."

            fi

            r1_list=("${read1[@]}")

            r2_list=("${read2[@]}")

            i1_list=()