如何在Go函数中正确传递参数？

This is a function from the Anaconda Go package:

func (a TwitterApi) GetHomeTimeline(v url.Values) (timeline []Tweet, err error) {
    if v == nil {
        v = url.Values{}
    }

    if val := v.Get("include_entities"); val == "" {
        v.Set("include_entities", "true")
    }

    response_ch := make(chan response)
    a.queryQueue <- query{a.baseUrl + "/statuses/home_timeline.json", v, &timeline, _GET, response_ch}
    return timeline, (<-response_ch).err
}

When I call the function like this, it works fine:

result, _ := api.GetHomeTimeline(nil)

But now I want to change the argument from nil into something else. In the example* this is set as:

v := url.Values{}
v.Set("count", "30")
result, _ := api.GetHomeTimeline(v)

But this generates the error: undefined: url in url.Values

* - I've set the example to match my request.

As reported in the comment, if someone else is looking for the answer, there is no mistake in the code above, just a missing import:

import "net/url"