>>> ur = UnifiedRegression(func='DecisionTree',
                           massive=True,
                           group_params={{'Group_1': {'percentage':0.6}, 'Group_2':{'percentage':0.8}})
>>> ur.fit(data=df,
           key='ID',
           features=['OUTLOOK' ,'TEMP', 'HUMIDITY','WINDY'],
           label='CLASS',
           group_key='GROUP_ID',
           background_size=4,
           group_params={'Group_1': {'background_random_state':2}})