def four_neighbors(self, row, col):
        """
        Returns horiz/vert neighbors of cell (row, col)
        """
        ans = []
        if row > 0:
            ans.append((row - 1, col))
        if row < self.grid_height - 1:
            ans.append((row + 1, col))
        if col > 0:
            ans.append((row, col - 1))
        if col < self.grid_width - 1:
            ans.append((row, col + 1))
        return ans