'Pull fullnames that represent instances of \'types\' out of items'

@classmethod
def desired_fullnames(cls, items):

    fullnames = set()
    type_ids = [type_._type_id for type_ in cls.types]
    for item in items:
        item_type = r2utils.decompose_fullname(item['fullname'])[1]
        if (item_type in type_ids):
            fullnames.add(item['fullname'])
    return fullnames
