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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 chunks(self):
 """Block dimensions for this dataset's data or None if it's not a dask array. """

        chunks = {}
        for v in self.variables.values():
            if v.chunks is not None:
                for dim, c in zip(v.dims, v.chunks):
                    if dim in chunks and c != chunks[dim]:
                        raise ValueError('inconsistent chunks')
                    chunks[dim] = c
        return Frozen(SortedKeysDict(chunks))