Validation checks used in samplers

The imbens.utils module includes various utilities.

check_neighbors_object(nn_name, nn_object[, ...])	Check the objects is consistent to be a NN.
check_sampling_strategy(sampling_strategy, ...)	Sampling target validation for samplers.
check_target_type(y[, indicate_one_vs_all])	Check the target types to be conform to the current samplers.