added attribute for opacity in create_pie function
0.12.0
added support for density contour chart and density heatmaps
0.10.1
added more transformers
0.8.0
added Constant value filler
0.7.1
added more tests and added more detailed documentation .
0.7.0
Added more tests Added a more comprehensive documentation Edited the features and preprocess modules changed the api for column_mean function, allowing the column_list parameter to be added