Pads `strdata` with a Request's callback argument, if specified, or does
    nothing.

def __pad(strdata):
    """ Pads `strdata` with a Request's callback argument, if specified, or does
    nothing.
    """
    if request.args.get('callback'):
        return "%s(%s);" % (request.args.get('callback'), strdata)
    else:
        return strdata