src/Phug/Optimizer.php
public function resolve($file)
    {
        return $this->locator->locate(
            $file,
            $this->paths,
            isset($this->options['extensions'])
                ? $this->options['extensions']
                : ['', '.pug', '.jade']
        );
    }
public function resolve($file)
    {
        return $this->locator->locate(
            $file,
            $this->paths,
            isset($this->options['extensions'])
                ? $this->options['extensions']
                : ['', '.pug', '.jade']
        );
    }
Resolve a template file path.

@param string $file

@return bool|null|string