Modifications to url in Golang

package main

import (
    "fmt"
    "log"
    "net/http"
    "net/url"
)

func main() {
    // This is just some example URL we received in our backend code.
    // Now we need to append some query params to it,
    // so that we can redirect or hit the newly formed URL.
    u := "https://www.example.com/path1/path2"

    // Scenario (1):
    // We just need to append path. For that we can just append "path" with simple string.
    // Before you add "/" check the URL has already or not
    pAppendedURL := u + "/pathN"
    if isValid, err := IsUrl(pAppendedURL); !isValid {
        log.Fatalf("Invalid URL: %v\n", err)
    }
    fmt.Printf("Appended path param to the URL: %s\n", pAppendedURL)

    // Scenario (2):
    // We need to append one or more query params.
    queryParms := url.Values{}
    queryParms.Add("key1", "value1")
    queryParms.Add("key2", "value2")

    // Append '?' if it does not exists already.
    qAppendedURL := u + "?" + queryParms.Encode()
    if isValid, err := IsUrl(qAppendedURL); !isValid {
        log.Fatalf("Invalid URL: %v\n", err)
    }
    fmt.Printf("Added query params to the URL: %s\n", qAppendedURL)

    // You may want to build request object like below
    // and redirect to the URL you built.
    req, err := http.NewRequest(http.MethodGet, qAppendedURL, nil)
    if err != nil {
        log.Fatalf("Failed to create request object: %v\n", err)
    }

    // Add request headers
    req.Header.Add("header1", "value1")
    req.Header.Add("header2", "value2")

    // So, you can redirect to the URL by new request object
    http.Redirect("your response writer goes here", req, qAppendedURL, 304)
}

// IsUrl checks if the URL is valid or not.
// https://stackoverflow.com/questions/25747580/ensure-a-uri-is-valid/25747925#25747925.
func IsUrl(str string) (bool, error) {
    u, err := url.Parse(str)
    return err == nil && u.Scheme != "" && u.Host != "", err
}