func Do(req *http.Request) (string, error) {
	response, err := httpClient.Do(req)
	if err != nil {
		return "", err
	}
	defer response.Body.Close()
	resBody, err := ioutil.ReadAll(response.Body)
	if err != nil {
		return "", err
	}
	if response.StatusCode < 200 || response.StatusCode > 299 {
		return "", ErrorHandling(resBody)
	}
	return string(resBody), nil
}
Do is used to execute an API Request.
package chargebee
import (
	"encoding/json"
	"errors"
	"io/ioutil"
	"net/http"
)
var httpClient = &http.Client{Timeout: DefaultHTTPTimeout}