path_prefix is an iterable (usually a list or a tuple) specifying a path or a path pattern of objects which the parser should extract from JSON. For instance, in the example above a path ('friends', 0 ...

When trying to tune a categorical parameter that is an iterable (in this case, hidden_layer_sizes in MLPClassifier, which are tuples), BayesSearchCV fails with the following exception: ~/anaconda3/ ...