def _target_ads_in_ad_group_to_user_list(
    client, customer_id, ad_group_id, user_list_resource_name
):
    """Creates an ad group criterion that targets a user list with an ad group.

    Args:
        client: an initialized GoogleAdsClient instance.
        customer_id: a str client customer ID used to create an ad group
            criterion.
        ad_group_id: a str ID for an ad group used to create an ad group
            criterion that targets members of a user list.
        user_list_resource_name: a str resource name for a user list.

    Returns:
        a str resource name for an ad group criterion.
    """
    ad_group_criterion_operation = client.get_type("AdGroupCriterionOperation")
    # Creates the ad group criterion targeting members of the user list.
    ad_group_criterion = ad_group_criterion_operation.create
    ad_group_criterion.ad_group = client.get_service(
        "AdGroupService"
    ).ad_group_path(customer_id, ad_group_id)
    ad_group_criterion.user_list.user_list = user_list_resource_name

    ad_group_criterion_service = client.get_service("AdGroupCriterionService")
    response = ad_group_criterion_service.mutate_ad_group_criteria(
        customer_id=customer_id, operations=[ad_group_criterion_operation]
    )
    resource_name = response.results[0].resource_name
    print(
        "Successfully created ad group criterion with resource name: "
        f"'{resource_name}' targeting user list with resource name: "
        f"'{user_list_resource_name}' and with ad group with ID "
        f"{ad_group_id}."
    )
    return resource_name
    # [END setup_remarketing_1]