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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 _candidates_from_grid(self, n=1000):
 """Get unused candidates from the grid or parameters."""

        used_vectors = set(tuple(v) for v in self.X)

        # if every point has been used before, gridding is done.
        grid_size = self.grid_width ** len(self.tunables)
        if len(used_vectors) == grid_size:
            return None

        all_vectors = set(itertools.product(*self._grid_axes))
        remaining_vectors = all_vectors - used_vectors
        candidates = np.array(list(map(np.array, remaining_vectors)))

        np.random.shuffle(candidates)
        return candidates[0:n]