def combine_top_features(results_dict, n_vars=None):
    """Combines the list of top features from different estimators
    into a single list where duplicates are removed.

    Args:
    -------------
        results_dict : dict
        n_vars : integer
    """
    if n_vars is None:
        n_vars = 1000
    combined_features = []
    for estimator_name in results_dict.keys():
        features = results_dict[estimator_name]
        combined_features.append(features)
    unique_features = list(set.intersection(*map(set, combined_features)))[:n_vars]

    return unique_features