space ={'max_depth': hp.quniform("x_max_depth", 4, 16, 1),
        'min_child_weight': hp.quniform ('x_min_child', 1, 10, 1),
        'subsample': hp.uniform ('x_subsample', 0.7, 1),
        'gamma' : hp.uniform ('x_gamma', 0.1,0.5),
        'colsample_bytree' : hp.uniform ('x_colsample_bytree', 0.7,1),
        'reg_lambda' : hp.uniform ('x_reg_lambda', 0,1)
    }