Thank you for all your reply and support. Neil's fits the most to me. I
shrinked it to this function:
def flatten(x):
for i in range(len(x)):
if isinstance(x[i], list):
x[i:i+1] = x[i]
Thank you all again. If someone could find even a cuter way, I'd like
to see that way.
Noud Aldenhoven