In progress
proc XOR args {
set work [lindex $args 0]
set args [lrange $args 1 end]
foreach item $args {
set work [expr $work ^ $item]
}
return $work
}
proc leftshift {current polynominals} {
set selected [list]
foreach selector $polynominals {
lappend selected [string index $current $selector]
}
set new_bit [XOR $selected]
return "[string range $current 1 end][set new_bit]"
}