Get exchange rate for two currencies

gistfile1.py

#!/usr/bin/env python
# Print exchange rate

import yql

QUERY = 'SELECT * FROM yahoo.finance.xchange WHERE pair in ("%s%s")'
ENV = "store://datatables.org/alltableswithkeys"

def main(argv=None):
    import sys
    from argparse import ArgumentParser

    argv = argv or sys.argv

    parser = ArgumentParser(description="")
    parser.add_argument("base", help="base currency")
    parser.add_argument("to", help="target currency")
    args = parser.parse_args(argv[1:])

    y = yql.Public()
    result = y.execute(QUERY % (args.base, args.to), env=ENV).one()
    print result["Rate"]

if __name__ == "__main__":
    main()