What you're describing is known as flattening a list, and with this new knowledge you'll be able to find many solutions to this on Google (there is no built-in flatten method). Here is one of them, from http://www.daniel-lemire.com/blog/archives/2006/05/10/flattening-lists-in-python/:
def flatten(x):
flat = True
ans = []
for i in x:
if ( i.__class__ is list):
ans = flatten(i)
else:
ans.append(i)
return ans
