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.

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)