docs: def _init_lsr(n_items, alpha, initial_params):
      """Initialize the LSR Markov chain and the weights."""
      if initial_params is None:
          weights = np.ones(n_items)
      else:
          weights = exp_transform(initial_params)
      chain = alpha * np.ones((n_items, n_items), dtype=float)
      return weights, chain