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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 _duplicates(list_):
 """Return dict mapping item -> indices."""

    item_indices = {}
    for i, item in enumerate(list_):
        try:
            item_indices[item].append(i)
        except KeyError:  # First time seen
            item_indices[item] = [i]
    return item_indices