'Return the enumeration member corresponding to the XML value
*xml_val*.'

@classmethod
def from_xml(cls, xml_val):

    if (xml_val not in cls._xml_to_member):
        raise InvalidXmlError(("attribute    value    '%s'    not    valid    for    this    type" % xml_val))
    return cls._xml_to_member[xml_val]
