post static method
Implementation
static Future<FxNetworkResponse> post(String url,
{Map<String, String>? headers, Object? body, Encoding? encoding}) async {
http.Response response = await http.post(
FxNetworkUtil.parseToUri(url, format: true),
headers: headers,
body: body,
encoding: encoding);
return FxNetworkResponse(response.body, response.statusCode, response);
}