features, feature_names = ft.dfs(entityset = es, target_entity = 'clients',
agg_primitives = ['mean', 'max', 'percent_true', 'last'],
trans_primitives = ['years', 'month', 'subtract', 'divide'])
ValueError: ('Unknown transform primitive years. ', 'Call ft.primitives.list_primitives() to get', ' a list of available primitives')

where are your source code??

hello，my firend.Recently, I've been studying your featuretools package and I have a question for you. About functions "remove_highly_correlated_features"，The documentation says:"We make the assumption that, for a pair of features, the feature that is further right in the feature matrix produced by dfs is the more complex one". I want to know, In the dfs, How to calculate the complexity of the features and then sort them？ Why the features on the right are more complex？ Thanks