Adds the given value list to the set mapped by the given key.
    If the key is missing from the dict, the given mapping is added.

    Example
    -------
    >>> dict_obj = {'a': set([1, 2])}
    >>> add_many_to_dict_val_set(dict_obj, 'a', [2, 3])
    >>> print(dict_obj['a'])
    {1, 2, 3}
    >>> add_many_to_dict_val_set(dict_obj, 'b', [2, 3])
    >>> print(dict_obj['b'])
    {2, 3}

def add_many_to_dict_val_set(dict_obj, key, val_list):
    """Adds the given value list to the set mapped by the given key.
    If the key is missing from the dict, the given mapping is added.

    Example
    -------
    >>> dict_obj = {'a': set([1, 2])}
    >>> add_many_to_dict_val_set(dict_obj, 'a', [2, 3])
    >>> print(dict_obj['a'])
    {1, 2, 3}
    >>> add_many_to_dict_val_set(dict_obj, 'b', [2, 3])
    >>> print(dict_obj['b'])
    {2, 3}
    """
    try:
        dict_obj[key].update(val_list)
    except KeyError:
        dict_obj[key] = set(val_list)