docs: def plot_predictions_histogram(Y_ph, Y, title=None):
      """Plot a histogram comparing int predictions vs true labels by class
  
      Args:
          Y_ph: An [n] or [n, 1] np.ndarray of predicted int labels
          Y: An [n] or [n, 1] np.ndarray of gold labels
      """
      labels = list(set(Y).union(set(Y_ph)))
      edges = [x - 0.5 for x in range(min(labels), max(labels) + 2)]
  
      plt.hist([Y_ph, Y], bins=edges, label=["Predicted", "Gold"])
      ax = plt.gca()
      ax.set_xticks(labels)
      plt.xlabel("Label")
      plt.ylabel("# Predictions")
      plt.legend(loc="upper right")
      if isinstance(title, str):
          plt.title(title)
      plt.show()