def METHOD_NAME(account_name: Account) -> Account:
    """Get the name of the leaf of this account.
    Args:
      account_name: A string, the name of the account whose leaf name to return.
    Returns:
      A string, the name of the leaf of the account.
    """
    assert isinstance(account_name, str)
    return account_name.split(sep)[-1] if account_name else None