###Latest version: 2v.3.0 (2019-2-28);   
Note, in version, the first and second numbering indicate compatibility (e.g., 2v.2.x).  

## 2v.3.0 (2020-1-13)  
* Minor sparse hash and memory usage optimization
* Improved fail safe notification in zlib compression. Identify loss during zlib compress large genome files.

## 2v.3.0 (2019-2-28)  
* Future proof and fully support user defined alphabets string [-k]. However, incompatible with previous versions.  
* Only binary version will be continued and supported, and the latest string version remain 2v.2.1

## 2v.2.1 (2018-9-21);  update the vocabulary size measure function [-V].
* Support range search using [-s] and [-e], and recursive search without specifying [-e] (default value = 0).  
* Limited user defined alphabets string support; recommended to use only built-in nucleotides and amino acids input.

## 2v.2.0 (2018-8); major update; adding more functions, a script optimization, and renaming functions  
* Two versions available and share same arguments and options, but the method of packing FF Profile is different and so they are not compatible. Each version has unique advantage over another, such as disk storage usage (FFP_txt) versus memory usage (FFP_bin).  
* Provide two way feature filtering: feature count and feature string entropy.