sub process_scheme{
    my ($output_file) = @_;
    open (OUTPUT_FILE, ">", $output_file) || die "cannot open log file";
    my $scheme_pid = open (SCHEME, "./t.pl | ") || die "cannot pipe scheme";
    my $str = "";
  MAIN:
    while (1) {
        eval{
            local $SIG{ALRM} = sub { die "alarm\n" }; # NB: \n required
            alarm 5;#$allow_time;
            if (eof(SCHEME)){    
                close OUTPUT_FILE; close SCHEME;
                last MAIN;
            }
            $str = <SCHEME>;
            alarm 0;
        };
        if ($@) {
            close OUTPUT_FILE;
            kill $scheme_pid;
            close SCHEME;
            return -$current_player;
        }

        # process the line
        print OUTPUT_FILE $str;
    }
    return 1;
}

##</code><code>##

while(1){};