The slice_gen generator takes one iterable and a start, stop and step values (all int, with the same meanings as the values in a slice: [start:stop:step], except start and stop must be non-negative and step must be positive; raise an AssetionError exception if any is not). It produces all the values in what would be the slice (without every putting all the values in a list and slicing it). For example

See Explaination

Explanation:

def slice_gen(iterable, start, stop, step):

it = iter(iterable)

if start < 0 or stop < 0 or step <= 0:

raise AssertionError

count = -1

nextI = start

while True:

count += 1

try:

item = next(it)

if count == stop:

break

elif count == nextI:

nextI = nextI + step

yield item

except:

return

for i in slice_gen('abcdefghijk', 3, 7, 1):

print(i, end='')

print("")

Using transistors instead of vacuum tubes in the second-generation computers drastically reduced  the size  of the computer size.

Explanation:

Transistors were smaller when compared to vacuum tubes so computers with vacuum tubes were small in size . They were also faster in speed, and cheaper to build. These computers also operates at lower temperature and produces less heat. In 1956, TX-0 was the first computer to build with transistors.Varieties of transistors under a single unit called Integrated Circuit Chip or ICs.  Increase in Memory size, increasing processing speed are the major achievements of ICs.