using RestSharp;


var options = new RestClientOptions("https://api.sandbox.{id}.gr4vy.app/card-scheme-definitions");
var client = new RestClient(options);
var request = new RestRequest("");
request.AddHeader("Authorization", "Bearer <token>");
var response = await client.GetAsync(request);

Console.WriteLine("{0}", response.Content);

package main

import (
	"fmt"
	"net/http"
	"io"
)

func main() {

	url := "https://api.sandbox.{id}.gr4vy.app/card-scheme-definitions"

	req, _ := http.NewRequest("GET", url, nil)

	req.Header.Add("Authorization", "Bearer <token>")

	res, _ := http.DefaultClient.Do(req)

	defer res.Body.Close()
	body, _ := io.ReadAll(res.Body)

	fmt.Println(string(body))

}

HttpResponse<String> response = Unirest.get("https://api.sandbox.{id}.gr4vy.app/card-scheme-definitions")
  .header("Authorization", "Bearer <token>")
  .asString();

<?php

$curl = curl_init();

curl_setopt_array($curl, [
  CURLOPT_URL => "https://api.sandbox.{id}.gr4vy.app/card-scheme-definitions",
  CURLOPT_RETURNTRANSFER => true,
  CURLOPT_ENCODING => "",
  CURLOPT_MAXREDIRS => 10,
  CURLOPT_TIMEOUT => 30,
  CURLOPT_HTTP_VERSION => CURL_HTTP_VERSION_1_1,
  CURLOPT_CUSTOMREQUEST => "GET",
  CURLOPT_HTTPHEADER => [
    "Authorization: Bearer <token>"
  ],
]);

$response = curl_exec($curl);
$err = curl_error($curl);

curl_close($curl);

if ($err) {
  echo "cURL Error #:" . $err;
} else {
  echo $response;
}

import requests

url = "https://api.sandbox.{id}.gr4vy.app/card-scheme-definitions"

headers = {"Authorization": "Bearer <token>"}

response = requests.get(url, headers=headers)

print(response.text)

const options = {method: 'GET', headers: {Authorization: 'Bearer <token>'}};

fetch('https://api.sandbox.{id}.gr4vy.app/card-scheme-definitions', options)
  .then(res => res.json())
  .then(res => console.log(res))
  .catch(err => console.error(err));

curl --request GET \
  --url https://api.sandbox.{id}.gr4vy.app/card-scheme-definitions \
  --header 'Authorization: Bearer <token>'

{
  "items": [
    {
      "type": "card-scheme-definition",
      "id": "visa",
      "icon_url": "https://api.sandbox.example.gr4vy.app/assets/card-scheme-definitions/visa.svg",
      "display_name": "Visa"
    }
  ]
}

{
  "type": "error",
  "code": "unauthorized",
  "status": 401,
  "message": "No valid API authentication found",
  "details": []
}