def _ds_search_ci_(ds, name):
    """Case insensitive search in data_vars and coords of a dataset

    Parameters
    ----------
    ds: xarray.Dataset
    name: str
        Requested name

    Returns
    -------
    str
        Real name
    """
    lname = name.lower()
    for cat in "data_vars", "coords":
        pool = getattr(ds, cat)
        names = [nm for nm in pool.keys()]
        lnames = [nm.lower() for nm in names]
        if lname in lnames:
            return names[lnames.index(lname)]