ch_left = ch_left ? ch_left : "["
ch_right = ch_right ? ch_right : "]"
ch_blank = ch_blank ? ch_blank : "-"
ch_used = ch_used ? ch_used : "|"
ch_left = ch_left ? ch_left : "["
ch_right = ch_right ? ch_right : "]"
ch_blank = ch_blank ? ch_blank : "-"
ch_used = ch_used ? ch_used : "|"