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Find Common Elements in List of Lists in Python

Return elements that appear in every sublist of a nested list, preserving duplicates with Counter intersection.

counter intersection nested-lists
Python 
from collections import Counter


def common_elements(list_of_lists):
    """Return elements present in every sublist."""
    if not list_of_lists:
        return []
    counts = Counter(list_of_lists[0])
    for sublist in list_of_lists[1:]:
        counts &= Counter(sublist)
    return list(counts.elements())


if _…
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