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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_dimensions(self, variables, unlimited_dims=None):
 """ This provides a centralized method to set the dimensions on the data store. Parameters variables : dict-like Dictionary of key/value (variable name / xr.Variable) pairs unlimited_dims : list-like List of dimension names that should be treated as unlimited dimensions. """

        if unlimited_dims is None:
            unlimited_dims = set()

        existing_dims = self.get_dimensions()

        dims = OrderedDict()
        for v in unlimited_dims:  # put unlimited_dims first
            dims[v] = None
        for v in variables.values():
            dims.update(dict(zip(v.dims, v.shape)))

        for dim, length in dims.items():
            if dim in existing_dims and length != existing_dims[dim]:
                raise ValueError(
                    "Unable to update size for existing dimension"
                    "%r (%d != %d)" % (dim, length, existing_dims[dim]))
            elif dim not in existing_dims:
                is_unlimited = dim in unlimited_dims
                self.set_dimension(dim, length, is_unlimited)