Validation checks used in ensembles

The imbens.utils module includes various utilities.

check_eval_datasets(eval_datasets[, ...])	Check eval_datasets parameter.
check_eval_metrics(eval_metrics)	Check parameter eval_metrics.
check_target_label_and_n_target_samples(y, ...)	Jointly check target_label and n_target_samples parameters.
check_balancing_schedule(balancing_schedule)	Check the balancing_schedule parameter.