src/Debug/FileStreamWrapper.php
public function stream_write($data)
    {
        if (!$this->handle) {
            return false;
        }
        self::restorePrev();
        $length = \fwrite($this->handle, $data);
        self::register();
        return $length;
    }
public function stream_write($data)
    {
        if (!$this->handle) {
            return false;
        }
        self::restorePrev();
        $length = \fwrite($this->handle, $data);
        self::register();
        return $length;
    }
Write to stream

@param string $data data to write

@return integer

@see http://php.net/manual/en/streamwrapper.stream-write.php