function to log events for themes in WordPress functions.php

log.php

/* LOG FUNCTION */
function log( $input ){
    $time = date('d-m-Y H:i T');

    $file = get_template_directory() . '/log.txt';
    $handle = fopen($file, 'a');
    $data = '--------------- ' . $time."--------------- \r\n".$input."\r\n";
    fwrite($handle, $data);
    fclose($handle);
}