How about this:
>>> l = [1,1,2,3,4,4,4,4,5,6,3,3,5,5,7,8,8,8,9,1,2,3,3,3,10,10]
>>>
>>> o = []
>>> p = None
>>> for n in l:
if n == p:
continue
o.append(n)
p = n
>>> o
[1, 2, 3, 4, 5, 6, 3, 5, 7, 8, 9, 1, 2, 3, 10]
Apparently, above solution is more verbose than OP's, so here is an alternative to that using zip_longest from itertools module:
>>> l
[1, 1, 2, 3, 4, 4, 4, 4, 5, 6, 3, 3, 5, 5, 7, 8, 8, 8, 9, 1, 2, 3, 3, 3, 10, 10]
>>> from itertools import zip_longest
>>> o = [p for p,n in zip_longest(l,l[1:]) if p != n] #By default fillvalue=None
>>> o
[1, 2, 3, 4, 5, 6, 3, 5, 7, 8, 9, 1, 2, 3, 10]
