Vendor/phpspreadsheet/phpoffice/phpspreadsheet/src/PhpSpreadsheet/Reader/Csv.php
protected function checkSeparator()
    {
        $line = fgets($this->fileHandle);
        if ($line === false) {
            return;
        }

        if ((strlen(trim($line, "\r\n")) == 5) && (stripos($line, 'sep=') === 0)) {
            $this->delimiter = substr($line, 4, 1);

            return;
        }

        return $this->skipBOM();
    }
protected function checkSeparator()
    {
        $line = fgets($this->fileHandle);
        if ($line === false) {
            return;
        }

        if ((strlen(trim($line, "\r\n")) == 5) && (stripos($line, 'sep=') === 0)) {
            $this->delimiter = substr($line, 4, 1);

            return;
        }

        return $this->skipBOM();
    }
Identify any separator that is explicitly set in the file.