def get_account_username_split(username):
    """
    Accepts the username for an unlinked InstitutionAccount
    and return a tuple containing the following:
      0: Account Type (e.g. 'cas')
      1: Institution Slug
      2: User ID for the institution
    """
    username_split = username.split("-")
    if len(username_split) < 3:
        raise ValueError("Value passed to get_account_username_split " +
                "was not the username for an unlinked InstitutionAccount.")
    slug = "-".join(username_split[1:len(username_split)-1])
    return (username_split[0], slug, username_split[len(username_split)-1])