def recalc(self, sheet=None):
        'reset column cache, attach to sheet, and reify name'
        if self._cachedValues:
            self._cachedValues.clear()
        if sheet:
            self.sheet = sheet
        self.name = self._name
def recalc ( self , sheet = None ) : if self . _cachedValues : self . _cachedValues . clear ( ) if sheet : self . sheet = sheet self . name = self . _name
reset column cache, attach to sheet, and reify name