def changekey(self, item):
        """For changing the casing of a key.
        If a key exists that is a caseless match for 'item' it will be changed to 'item'.
        This is useful when initially setting up default keys - but later might want to preserve an alternative casing.
        (e.g. if later read from a config file - and you might want to write back out with the user's casing preserved).
        """
        key = self.findkey(item)           # does the key exist
        if key == None: raise KeyError(item)
        temp = self[key]
        del self[key]
        self[item] = temp
        self._keydict[item.lower()] = item
For changing the casing of a key.
        If a key exists that is a caseless match for 'item' it will be changed to 'item'.
        This is useful when initially setting up default keys - but later might want to preserve an alternative casing.
        (e.g. if later read from a config file - and you might want to write back out with the user's casing preserved).
        
recipes/Python/283455_caselessDict/recipe-283455.py