You can use itertools.groupby:
>>> import itertools
>>> [key for key, grp in itertools.groupby([1, 2, 2, 3])]
[1, 2, 3]
itertools.groupby returns an iterator. By iterating it, you will get a key, group pairs. (key will be a item if no key function is specified, otherwise the return value of the key function). group is an iterator which will yields items grouped by applying key function (if not specified, same values will be grouped)
>>> import itertools
>>> it = itertools.groupby([1, 2, 2, 3])
>>> it
>>> for key, grp in it:
... print(key)
... print(grp)
...
1
2
3
>>> it = itertools.groupby([1, 2, 2, 3])
>>> for key, grp in it:
... print(list(grp))
...
[1]
[2, 2]
[3]
Above solution, I used only key because the question does not care how many items are adjacent.
