def kvdict2str(d, sep='@', dlm='::'):
    """Turns a key-value dict into a string.
    Keys and values are separated using `sep` [default '@'].
    Each key-value pair is delimited using `dlm` [default '::'].
    """
    ret = '::'.join('%s@%s' % (k, v) for k, v in d.iteritems())
    return ret