ds_map_access

///@desc Accesses a map .
///@param map
///@param keys...

var ds = argument[0];

var key = undefined;
var val = undefined;

for (var i=1;i<argument_count;i++) {
    key = argument[i];
    val = ds[? key];

    if (is_undefined(val)) {
        // we failed to find a nested value
        // just return it now

        return undefined;
    }

    if (i < argument_count-1) {
        if ds_exists(val, ds_type_map) {
            // we're not at the last argument, so change the map target
            // AND
            // a map exists at the value we requested

            ds = val;
        }
    }
}

return val;