the Moore neighborhood

求矩陣中任一點鄰居爲1 的數量：

def count_neighbours(grid, row, col):
    NEIGHBORS = ((-1, -1), (-1, 0), (-1, 1), (0, -1),
              (0, 1), (1, -1), (1, 0), (1, 1))
    count = 0
    for diff in NEIGHBORS:
        n_row = row + diff[0]
        n_col = col + diff[1]
        if 0<=n_row<len(grid) and 0<=n_col<len(grid[0]):
            if grid[n_row][n_col]:
                count+=1
    return count

if __name__ == '__main__':
    #These "asserts" using only for self-checking and not necessary for auto-testing
    assert count_neighbours(((1, 0, 0, 1, 0),
                             (0, 1, 0, 0, 0),
                             (0, 0, 1, 0, 1),
                             (1, 0, 0, 0, 0),
                             (0, 0, 1, 0, 0),), 1, 2) == 3, "1st example"
    assert count_neighbours(((1, 0, 0, 1, 0),
                             (0, 1, 0, 0, 0),
                             (0, 0, 1, 0, 1),
                             (1, 0, 0, 0, 0),
                             (0, 0, 1, 0, 0),), 0, 0) == 1, "2nd example"
    assert count_neighbours(((1, 1, 1),
                             (1, 1, 1),
                             (1, 1, 1),), 0, 2) == 3, "Dense corner"
    assert count_neighbours(((0, 0, 0),
                             (0, 1, 0),
                             (0, 0, 0),), 1, 1) == 0, "Single"