* @return $streamData The compressed stream data
* @throws InvalidArgumentException If the stream is not compressable or decompressable
*/
- function compressStream ($streamData);
+ function compressStream (string $streamData);
/**
* A decompression stream
* @return $streamData The decompressed stream data
* @throws InvalidArgumentException If the stream is not compressable or decompressable
*/
- function decompressStream ($streamData);
+ function decompressStream (string $streamData);
/**
* Getter for the file extension of this compressor