function cellToCenterChild(h3Index, res) {
    const [lower, upper] = h3IndexToSplitLong(h3Index);
    const centerChild = C._malloc(SZ_H3INDEX);
    try {
        throwIfError(H3.cellToCenterChild(lower, upper, res, centerChild));
        return validateH3Index(readH3IndexFromPointer(centerChild));
    } finally {
        C._free(centerChild);
    }
}
Get the center child of the given hexagon at a particular resolution
@static
@param  {H3IndexInput} h3Index  H3 index to get center child for
@param  {number} res       Resolution of cell to return
@return {H3Index}          H3 index of child, or null for invalid input
@throws {H3Error}          If resolution is invalid