docs: def get_central_coors(self, row, col):
          """Get the coordinates of central grid.
  
          Args:
              row: row number, range from 0 to (nRows - 1).
              col: col number, range from 0 to (nCols - 1).
  
          Returns:
              XY coordinates. If the row or col are invalid, raise ValueError.
          """
          if row < 0 or row >= self.nRows or col < 0 or col >= self.nCols:
              raise ValueError("The row (%d) or col (%d) must be >=0 and less than "
                               "nRows (%d) or nCols (%d)!" % (row, col, self.nRows, self.nCols))
          else:
              tmpx = self.xMin + (col + 0.5) * self.dx
              tmpy = self.yMax - (row + 0.5) * self.dx
              return tmpx, tmpy