Removes consecutive duplicate elements.
DeleteAdjacentDuplicates[list]
DeleteAdjacentDuplicates[list, test]
DeleteAdjacentDuplicates[{1, 1, 2, 2, 3, 1, 1}]
→ {1, 2, 3, 1}DeleteAdjacentDuplicates[{1, 2, 4, 7}, Abs[#1 - #2] < 3 &]
→ {1, 7}DeleteAdjacentDuplicates[Association[a -> 1, b -> 1, c -> 2, d -> 2, e -> 1]]
→ <|a -> 1, c -> 2, e -> 1|>