Fatal error: Uncaught Error: Undefined constant "STDERR" in /var/www/html/tennisdata/PHPlot/test/compare_tests.php:29 Stack trace: #0 /var/www/html/tennisdata/PHPlot/test/compare_tests.php(185): usage() #1 {main} thrown in /var/www/html/tennisdata/PHPlot/test/compare_tests.php on line 29