docs: def view_label_matrix(L, colorbar=True):
      """Display an [n, m] matrix of labels"""
      L = L.todense() if sparse.issparse(L) else L
      plt.imshow(L, aspect="auto")
      plt.title("Label Matrix")
      if colorbar:
          labels = sorted(np.unique(np.asarray(L).reshape(-1, 1).squeeze()))
          boundaries = np.array(labels + [max(labels) + 1]) - 0.5
          plt.colorbar(boundaries=boundaries, ticks=labels)
      plt.show()