'Set a new preference of a user for a specific item with a certain
magnitude.
Parameters
user_id: int or string
User for which the preference will be updated.
item_id: int or string
Item that will be updated.
value:  The new magnitude for the preference of a item_id from a
user_id.'

def set_preference(self, user_id, item_id, value):

    self.model.set_preference(user_id, item_id, value)
