def interaction_features_to_dict(df):
    """ From a df of the form base feature | Interaction Term return a nested 
        dictionary of the form {basefeature:[feature1, feature2, feature3]}
    """
    interactions_dict = {}
    for base_feature in df.Base_Feature.unique():
        int_terms = df[df.Base_Feature.isin([base_feature])].Interaction_Term.values.tolist()
        interactions_dict[base_feature] = int_terms
    return interactions_dict