def has_external_choices(json_struct):
    """
    Returns true if a select one external prompt is used in the survey.
    """
    if isinstance(json_struct, dict):
        for k, v in json_struct.items():
            if k == "type" and isinstance(v, str) and v.startswith("select one external"):
                return True
            elif has_external_choices(v):
                return True
    elif isinstance(json_struct, list):
        for v in json_struct:
            if has_external_choices(v):
                return True
    return False