Remove consecutive duplicate values from a list while preserving the order of first occurrences. Non-consecutive duplicates should remain in the result.
Examples:
Input: nums = [1,1,2,3,3,3,2,2,1]
Output: [1,2,3,2,1]
Explanation: Consecutive duplicates are removed, but non-consecutive duplicates remain
Input: nums = [1,2,3,4,5]
Output: [1,2,3,4,5]
Explanation: No consecutive duplicates exist in the input
Input: nums = [1,1,1,1]
Output: [1]
Explanation: All consecutive duplicates removed, leaving one element
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