def load (filename):
global CARD_BY_NAME
global CARD_BY_ID
CARD_BY_NAME = {}
CARD_BY_ID = {}
reader = DictReader(open(filename, 'r'), delimiter = '\t')
for row in reader:
card = Card.from_csv(row)
if card.name not in CARD_BY_NAME:
CARD_BY_NAME[card.name] = card
if card.id in CARD_BY_ID:
raise Exception('Duplicate card IDs: %d' % card.id)
CARD_BY_ID[card.id] = card
