docs: def _populate_tournament_payoff_array1(payoff_array, k):
      """
      Populate `payoff_array` with the payoff values for player 1 in the
      tournament game.
  
      Parameters
      ----------
      payoff_array : ndarray(float, ndim=2)
          ndarray of shape (m, n), where m = n choose k, prefilled with
          zeros. Modified in place.
      k : scalar(int)
          Size of the subsets of nodes.
  
      """
      m = payoff_array.shape[0]
      X = np.arange(k)
      for j in range(m):
          for i in range(k):
              payoff_array[j, X[i]] = 1
          X = next_k_array(X)