PHPCfg\Visitor\VariableFinder::enterOp PHP Method

    public function enterOp(Op $op, Block $block)
    {
        foreach ($op->getVariableNames() as $name) {
            $var = $op->{$name};
            if (!is_array($var)) {
                $var = [$var];
            }
            foreach ($var as $v) {
                if (is_null($v)) {
                    continue;
                }
                $this->variables->attach($v);
            }
        }
    }