Vendor/phpspreadsheet/phpoffice/phpspreadsheet/src/PhpSpreadsheet/Calculation/TextData.php
public static function LEFT($value = '', $chars = 1)
    {
        $value = Functions::flattenSingleValue($value);
        $chars = Functions::flattenSingleValue($chars);

        if ($chars < 0) {
            return Functions::VALUE();
        }

        if (is_bool($value)) {
            $value = ($value) ? Calculation::getTRUE() : Calculation::getFALSE();
        }

        return mb_substr($value, 0, $chars, 'UTF-8');
    }
public static function LEFT($value = '', $chars = 1)
    {
        $value = Functions::flattenSingleValue($value);
        $chars = Functions::flattenSingleValue($chars);

        if ($chars < 0) {
            return Functions::VALUE();
        }

        if (is_bool($value)) {
            $value = ($value) ? Calculation::getTRUE() : Calculation::getFALSE();
        }

        return mb_substr($value, 0, $chars, 'UTF-8');
    }
LEFT.

@param string $value Value
@param int $chars Number of characters

@return string