beginRequest method
Implementation
Uri beginRequest(
String route, Map<String, dynamic> query, DataOperation operation) {
var url =
<String>[path, route + mountQueryParameters(query)].reduce((val, el) {
return val + (el.startsWith('/') ? el : '/$el');
});
var uri = Uri.parse(url);
onSend?.call(APIRequest(uri, headers, operation, data: query));
return Uri.parse(url);
}