'Based on the element, figures out how to check/convert the attribute value
All values are converted to string'

def convert(self, attribute, value, element):

    conversion = attrconverters.get((attribute, element.qname), None)
    if (conversion is not None):
        return conversion(attribute, value, element)
    else:
        conversion = attrconverters.get((attribute, None), None)
        if (conversion is not None):
            return conversion(attribute, value, element)
    return str(value)
