Parse data from Yahoo.

def yahoo(base, target):
    """Parse data from Yahoo."""
    api_url = 'http://download.finance.yahoo.com/d/quotes.csv'
    resp = requests.get(
        api_url,
        params={
            'e': '.csv',
            'f': 'sl1d1t1',
            's': '{0}{1}=X'.format(base, target)
        },
        timeout=1,
    )
    value = resp.text.split(',', 2)[1]
    return decimal.Decimal(value)