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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 _merge_simple(adjustment_lists, front_idx, back_idx):
 """ Merge lists of new and existing adjustments for a given index by appending or prepending new adjustments to existing adjustments. Notes ----- This method is meant to be used with ``toolz.merge_with`` to merge adjustment mappings. In case of a collision ``adjustment_lists`` contains two lists, existing adjustments at index 0 and new adjustments at index 1. When there are no collisions, ``adjustment_lists`` contains a single list. Parameters adjustment_lists : list[list[Adjustment]] List(s) of new and/or existing adjustments for a given index. front_idx : int Index of list in ``adjustment_lists`` that should be used as baseline in case of a collision. back_idx : int Index of list in ``adjustment_lists`` that should extend baseline list in case of a collision. Returns ------- adjustments : list[Adjustment] List of merged adjustments for a given index. """

    if len(adjustment_lists) == 1:
        return list(adjustment_lists[0])
    else:
        return adjustment_lists[front_idx] + adjustment_lists[back_idx]