docs: def _preprocess_inputs(x, weights):
      """
      Coerce inputs into compatible format
      """
      if weights is None:
          w_arr = np.ones(len(x))
      else:
          w_arr = np.array(weights)
      x_arr = np.array(x)
      if x_arr.ndim == 2:
          if w_arr.ndim == 1:
              w_arr = w_arr[:, np.newaxis]
      return x_arr, w_arr