def add_user_to_group(group, role, email):
uri = "<STR_LIT>".format(group, role, email)<EOL>return __put(uri)<EOL>
Add a user to a group the caller owns

    Args:
        group (str): Group name
        role (str) : Role of user for group; either 'member' or 'admin'
        email (str): Email of user or group to add

    Swagger:
        https://api.firecloud.org/#!/Groups/addUserToGroup