- Added 
fetch_sparse_values() function. 
- Updated treehouse URL.
 
- Added treehouse datasets.
 
- Fixed bug about an error happened when querying mutation data.
 
- Dropped “Treehouse” data hub.
 
- Updated code to update Xena hub datasets.
 
- Added 
max_try option in query and download functions, so they can handle internet connection issue better 
- Added a new data hub: PCAWG Xena Hub (#24).
 
- Added a new data hub: Kids First Xena Hub (#24).
 
- Updated data update function more robustly.