def pandas_index_dtypes() -> st.SearchStrategy[np.dtype]:
    """
    Dtypes supported by pandas indexes.
    Restrict datetime64 and timedelta64 to ns frequency till Xarray relaxes that.
    """
    return (
        npst.integer_dtypes(endianness="=", sizes=(32, 64))
        | npst.unsigned_integer_dtypes(endianness="=", sizes=(32, 64))
        | npst.floating_dtypes(endianness="=", sizes=(32, 64))
        # TODO: unset max_period
        | npst.datetime64_dtypes(endianness="=", max_period="ns")
        # TODO: set max_period="D"
        | npst.timedelta64_dtypes(endianness="=", max_period="ns")
        | npst.unicode_string_dtypes(endianness="=")
    )

    Dtypes supported by pandas indexes.
    Restrict datetime64 and timedelta64 to ns frequency till Xarray relaxes that.
    
xarray/testing/strategies.py