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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 _set_index(self, key, index):
 """Set a new index array for this series """

        axis = key[0]
        origin = "{}0".format(axis)
        delta = "d{}".format(axis)
        if index is None:
            return delattr(self, key)
        if not isinstance(index, Index):
            try:
                unit = index.unit
            except AttributeError:
                unit = getattr(self, "_default_{}unit".format(axis))
            index = Index(index, unit=unit, copy=False)
        setattr(self, origin, index[0])
        if index.regular:
            setattr(self, delta, index[1] - index[0])
        else:
            delattr(self, delta)
        setattr(self, "_{}".format(key), index)