docs: def _pivoting(tableau, pivot, pivot_row):
      """
      Perform a pivoting step. Modify `tableau` in place.
  
      Parameters
      ----------
      tableau : ndarray(float, ndim=2)
          Array containing the tableau.
  
      pivot : scalar(int)
          Pivot.
  
      pivot_row : scalar(int)
          Pivot row index.
  
      Returns
      -------
      tableau : ndarray(float, ndim=2)
          View to `tableau`.
  
      """
      nrows, ncols = tableau.shape
  
      pivot_elt = tableau[pivot_row, pivot]
      for j in range(ncols):
          tableau[pivot_row, j] /= pivot_elt
  
      for i in range(nrows):
          if i == pivot_row:
              continue
          multiplier = tableau[i, pivot]
          if multiplier == 0:
              continue
          for j in range(ncols):
              tableau[i, j] -= tableau[pivot_row, j] * multiplier
  
      return tableau