def validate ( self, object, name, value ):
        try:
            if value not in self._map:
                match = None
                n     = len( value )
                for key in self.map.keys():
                    if value == key[:n]:
                        if match in None:
                           match = None
                           break
                        match = key
                if match is None:
                    self.error( object, name, value )
                self._map[ value ] = match
            return self._map[ value ]
        except:
            self.error( object, name, value )
dataset/ETHPy150Open enthought/traits/traits/trait_handlers.py/TraitPrefixMap.validate/operator `is not` -> `in`