(grid_sums, x1, y1, x2, y2)
return grid_sums[y2][x2] + grid_sums[y1][x1] - grid_sums[y2][x1] - grid_sums[y1][x2]
calcs the power between top left corner x1, y1 and bottom right corner x2, y2
calcs the power between top left corner x1, y1 and bottom right corner x2, y2
calcs the power between top left corner x1 y1 and bottom right corner x2 y2
def power_between(grid_sums, x1, y1, x2, y2):
    """ calcs the power between top left corner x1, y1 and bottom right corner x2, y2"""
    return grid_sums[y2][x2] + grid_sums[y1][x1] - grid_sums[y2][x1] - grid_sums[y1][x2]
def power_between ( grid_sums , x1 , y1 , x2 , y2 ) : return grid_sums [ y2 ] [ x2 ] + grid_sums [ y1 ] [ x1 ] - grid_sums [ y2 ] [ x1 ] - grid_sums [ y1 ] [ x2 ]