'Verify writing at an offset actually writes to that offset.'

def test_correct_offset(self):

    self.run_esptool('write_flash    0x2000    images/sector.bin')
    time.sleep(0.1)
    three_sectors = self.readback(0, 12288)
    last_sector = three_sectors[8192:]
    with open('images/sector.bin', 'rb') as f:
        ct = f.read()
    self.assertEqual(last_sector, ct)
