code: def _check_predictions(predictions):
      """Check if the predictions array has the correct size.
  
      Raises a value error if the array do not contain exactly 3 dimensions:
      [n_samples, n_classifiers, n_classes]
  
      """
      if predictions.ndim != 3:
          raise ValueError(
              "predictions must contain 3 dimensions: "
              "[n_samples, n_classifiers, n_classes]. Currently"
              "predictions has {} dimensions".format(predictions.ndim)
          )
  
imports: import numpy
  from scipy.stats.mstats import mode
  from sklearn.utils.validation import check_array
  from deslib.util.prob_functions import softmax
label_desc: Use image node_id 21 for calling a global function with example usage: _check_predictions(predictions) without return types