def create_day_set(phrase, recurrence_dict):
    """Create a Set of recurrence days from utterance.

    Arguments:
        phrase (Str): user utterance
        recurrence_dict (Dict): map of strings to recurrence patterns

    Returns:
        Set: days as integers
    """
    recur = set()
    for recurrence in recurrence_dict:
        if recurrence in phrase:
            for day in recurrence_dict[recurrence].split():
                recur.add(day)
    return recur