from sklearn.model_selection import GridSearchCV

# Comprehensive parameter grid
param_grid = {
    'max_depth': [3, 5, 7, 9],
    'learning_rate': [0.01, 0.05, 0.1, 0.2],
    'n_estimators': [100, 200, 400, 800],
    'subsample': [0.7, 0.8, 0.9, 1.0],
    'colsample_bytree': [0.7, 0.8, 0.9, 1.0],
    'min_child_weight': [1, 3, 5, 7],
    'gamma': [0, 0.1, 0.5, 1.0]
}

        __
        __