title: problem in making http.get() request in flutter
body: <p>i am learing about api's and http request in flutter and i am facing problem in making a get request as in any tutorial they are directly pasting string url inside get as parameter but when i post it as string it is showing error: The argument type 'String' can't be assigned to the parameter type 'Uri'.</p>
  <p>can any one help me in this :
  this is my sample code :</p>
  <pre><code>import 'dart:convert' as convert;
  import 'package:http/http.dart' as http;
  
  void main(List&lt;String&gt; arguments) async {
    // This example uses the Google Books API to search for books about http.
    // https://developers.google.com/books/docs/overview
    var url = 'https://www.googleapis.com/books/v1/volumes?q={http}';
  
    // Await the http get response, then decode the json-formatted response.
    var response = await http.get(url); // i am getting error here
    if (response.statusCode == 200) {
      var jsonResponse = convert.jsonDecode(response.body);
      var itemCount = jsonResponse['totalItems'];
      print('Number of books about http: $itemCount.');
    } else {
      print('Request failed with status: ${response.statusCode}.');
    }
  }
  </code></pre>
  <p>here is image of my code with error</p>
  <p><a href="https://i.stack.imgur.com/SMrlA.png" rel="nofollow noreferrer">enter image description here</a></p>