+
+ sub unq {
+ my $seq = shift;
+ my %es = ( # character escape codes, aka escape sequences
+ 't' => "\t", # tab (HT, TAB)
+ 'n' => "\n", # newline (NL)
+ 'r' => "\r", # return (CR)
+ 'f' => "\f", # form feed (FF)
+ 'b' => "\b", # backspace (BS)
+ 'a' => "\a", # alarm (bell) (BEL)
+ 'e' => "\e", # escape (ESC)
+ 'v' => "\013", # vertical tab (VT)
+ );
+
+ if ($seq =~ m/^[0-7]{1,3}$/) {
+ # octal char sequence
+ return chr(oct($seq));
+ } elsif (exists $es{$seq}) {
+ # C escape sequence, aka character escape code
+ return $es{$seq}
+ }
+ # quoted ordinary character
+ return $seq;
+ }
+