def append_order_by_clauses(executable, order_by_clauses):
    """Add ORDER BY SQLAlchemy Column objects to a Select object.

    :param executable: SQLAlchemy executable query object.
    :type executable: Select
    :param order_by_clauses: MySQL ORDER BY clause-related SQLAlchemy object(s).
    :type order_by_clauses: Column
    :type order_by_clauses: list
    :returns: MySQL expression-related SQLAlchemy exectuable.
    :rtype: Select
    """
    if order_by_clauses is None:
        return executable
    if isinstance(order_by_clauses, list):
        for clause in order_by_clauses:
            executable = executable.order_by(clause)
    else:
        executable = executable.order_by(order_by_clauses)
    return executable
