docs: def api_key(request, response, verify_user, context=None, **kwargs):
      """API Key Header Authentication
  
      The verify_user function passed in to ths authenticator shall receive an
      API key as input, and return a user object to store in the request context
      if the request was successful.
      """
      api_key = request.get_header('X-Api-Key')
  
      if api_key:
          try:
              user = verify_user(api_key)
          except TypeError:
              user = verify_user(api_key, context)
          if user:
              return user
          else:
              return False
      else:
          return None