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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_gt(self, item):
        'Return first item with a key > item.  Raise ValueError if not found'
        k = self._key(item)
        i = bisect_right(self._keys, k)
        if i != len(self):
            return self._items[i]
        raise ValueError('No item found with key above: %r' % (k,))