src/I18n/TranslationPromise.php
public function translate($language = null)
    {
        if (isset($language)) {
            $this->language = $language;
        } else {
            $this->suggestLanguage();
        }
        return Reaction::t($this->category, $this->message, $this->params, $this->language);
    }
public function translate($language = null)
    {
        if (isset($language)) {
            $this->language = $language;
        } else {
            $this->suggestLanguage();
        }
        return Reaction::t($this->category, $this->message, $this->params, $this->language);
    }
Translate message to given language.
Or suggest language by backtrace
@param string|null $language
@return string