Find BTC balance for an address in Go

I need to correct and transform a function, to checking 2 addresses of btc balance, like (addr and addr1 ), and the return is json value, i need to specify im not know very well golang.. need help!

func balance(addr) {
	var url = "https://bitcoin.toshi.io/api/v0/addresses/" + addr
	response, _ := http.Get(url)
	defer response.Body.Close()
	contents, _ := ioutil.ReadAll(response.Body)
	return contents
}

EDIT:

i need a function to get balances of 2 btc addresses, or to use this libraries btcwallet.

func GetAddressBalance(icmd btcjson.Cmd) (interface{}, *btcjson.Error) 
func GetAddressesByAccount(icmd btcjson.Cmd) (interface{}, *btcjson.Error) 
func GetBalance(icmd btcjson.Cmd) (interface{}, *btcjson.Error) 

You were on the right track. The api returns a json. This can be unmarshalled into a struct (Address). That way you can access everything returned by the api. Do not forget to always check for error codes! Replace some_address with an actual address to get the balance.

package main

import (
	"encoding/json"
	"fmt"
	"net/http"
)

func main() {
	a, err := getAddress("some_address")
	if err != nil {
		fmt.Println(err)
		return
	}
	fmt.Println("Balance:", a.Balance)
}

type Address struct {
	Hash                string
	Balance             int
	Received            int
	Send                int
	UnconfirmedBalance  int `json:"unconfirmed_balance"`
	UnconfirmedReceived int `json:"unconfirmed_received"`
	UnconfirmedSent     int `json:"unconfirmed_sent"`
}

func getAddress(addr string) (*Address, error) {
	resp, err := http.Get("https://bitcoin.toshi.io/api/v0/addresses/" + addr)
	if err != nil {
		return nil, err
	}
	defer resp.Body.Close()

	if resp.StatusCode != http.StatusOK {
		return nil, fmt.Errorf("Error: %v", http.StatusText(resp.StatusCode))
	}

	var address Address
	decoder := json.NewDecoder(resp.Body)
	if err := decoder.Decode(&address); err != nil {
		return nil, err
	}

	return &address, nil
}