>>> ur = UnifiedRegression(func='DecisionTree',
                           multi_class=True,
                           massive=True,
                           thread_ratio=0.5,
                           group_params={{'Group_1': {'percentage':0.6}})
>>> 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}})