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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 find_lt(self, k):
 """Return last item with a key < k. Raise ValueError if not found. """

        i = bisect_left(self._keys, k)
        if i:
            return self._items[i - 1]
        raise ValueError('No item found with key below: %r' % (k,))