Explanation:
def letterDigitCount(j):
dic={"digits":0,"letters":0}
for a in j:
if a.isdigit():
dic["digits"]+=1
elif a.isalpha():
dic["letters"]+=1
return dic
That would be a star network. A star network isn't necessarily shaped like a star, of course, but like you mention this topology has a central device, usually a server of some sorts, and then many different endpoints coming out of that central device, such as the client computers for the server.
Gas giants DO have rings and satellites.
It's true.