docs: def calculateOutletSlope(self):
          """
          Attempt to determine the slope at the OUTLET
          """
          try:
              mask_grid = self.getGrid()
              elevation_grid = self.getGrid(use_mask=False)
  
              outrow = int(self.getCard("OUTROW").value)-1
              outcol = int(self.getCard("OUTCOL").value)-1
              cell_size = float(self.getCard("GRIDSIZE").value)
  
              min_row = max(0, outrow-1)
              max_row = min(mask_grid.x_size, outrow+2)
              min_col = max(0, outcol-1)
              max_col = min(mask_grid.y_size, outcol+2)
  
              mask_array = mask_grid.np_array()
              mask_array[outrow, outcol] = 0
              mask_array = mask_array[min_row:max_row, min_col:max_col]
              mask_array = (mask_array==0)
  
              elevation_array = elevation_grid.np_array()
              original_elevation = elevation_array[outrow, outcol]
              elevation_array = elevation_array[min_row:max_row, min_col:max_col]
  
              slope_calc_array = (elevation_array-original_elevation)/cell_size
              #NOTE: Ignoring distance to cells at angles. Assuming to small to matter
              mask_array[slope_calc_array<=0] = True
  
              slope_mask_array = np.ma.array(slope_calc_array, mask=mask_array)
              outslope = slope_mask_array.mean()
              if outslope is np.ma.masked or outslope < 0.001:
                  outslope = 0.001
  
          except ValueError:
              outslope = 0.001
  
          self.setCard("OUTSLOPE", str(outslope))