I found a great site hackinscience org, with 70 python problems to work through.
problem 17, requires returning the possible two letter pairs without doubles such as aa, bb. from a - z.
this script does this however, I keep getting an error message that states, what about b a? the script returns b a!!
import string
x=string.ascii_lowercase
y=list(x)
for i in y:
for g in y:
if i != g:
print(i,g)