public static function formatStackFrame($index, array $frame)
{
$stack = '';
if (isset($frame['file']) && isset($frame['line']) && isset($frame['function'])) {
$stack .= "#{$index} {$frame['file']} ({$frame['line']}): ";
if (isset($frame['class'])) {
$stack .= $frame['class'] . "->";
}
$stack .= $frame['function'] . "()" . PHP_EOL;
}
return $stack;
}