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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def _split_diff(merge_result, context_lines=3):
 """Split diffs and context lines into groups based on None sentinel"""

    collect = []
    for item in _visible_in_diff(merge_result, context_lines=context_lines):
        if item is None:
            if collect:
                yield collect
            collect = []
        else:
            collect.append(item)