[VEX] uniqueval, nuniqueval

uniqueval()

int|string uniqueval(<geometry>geometry, string attribclass, string attribute_name, int which)

i.g.)

int count = nuniqueval(0, "point", "foo");
for (int i = 0; i < count; i++) {
    string val = uniqueval(0, "point", "foo", i);
    // ...do something with the value...
}

nuniqueval()

int  nuniqueval(<geometry>geometry, string attribclass, string attribute_name)

i.g.)

int test = nuniqueval(0, "point", "foo") == npoints(0)