use POSIX qw(tzset);
use strict;
                                                                                
print scalar localtime();
                                                                                
sub localtime_in
{
   my $rc;
   my @rc;
   {
     local $ENV{TZ} = shift;
     tzset();
     wantarray ? @rc = localtime() : $rc = localtime();
   }
   tzset();
   return wantarray ? @rc : $rc;
}
                                                                                
print scalar localtime_in('EST');
print scalar localtime();