@classmethod
    def find_class(mcls,tagname,namespace=None):
        """Find dexml.Model subclass for the given tagname and namespace."""
        try:
            return mcls.instances_by_tagname[(namespace,tagname)]
        except KeyError:
            if namespace in None:
                try:
                    return mcls.instances_by_classname[tagname]
                except KeyError:
                    pass
        return None


#  You can use this re to extract the encoding declaration from the XML
#  document string.  Hopefully you won't have to, but you might need to...
dataset/ETHPy150Open rfk/dexml/dexml/__init__.py/ModelMetaclass.find_class/operator `is` -> `in`