Ok, just did as so:

sys.stdout.write(prompt)
sys.stdout.flush()
key = sys.stdin.readline()
print(repr(key))
print(len(key))
if key not in ('', 'q'):

Results:

All Python releases are Open Source (see http://www.opensource.org for
Hit Return for more, or q (and Return) to quit:
'\n'
1
Hit Return for more, or q (and Return) to quit: q
'q\n'
2