input: 
  from typing import Dict, Any
  
  def make_api_request(url: str, headers: Dict[str, str]) -> str:
      """
      Sends a GET request to the specified URL with the given headers and parses the JSON response. 
      The function should return a formatted string of user data from the response.
      
      >>> make_api_request('https://api.example.com/users', {'Authorization': 'Bearer YOUR_API_TOKEN', 'Content-Type': 'application/json'})
      "User1, User2, User3"
      """
  
output:     import requests
      import json
  
      response = requests.get(url, headers=headers)
      if response.status_code == 200:
          data = response.json()
          users = [user['name'] for user in data['users']]
          return ', '.join(users)
      else:
          return "Error: Unable to fetch data"