>>> d = {'a':1,'b':2,'c':3}
            >>> print d.exclude_keys('b,c,d')
            >>> {'a':1}
            >>> d = {'a':1,'b':2,'c':3}
            >>> print d.exclude_keys(['b','c','d'])
            >>> {'a':1}

def exclude_keys(self,key_list):
        """ >>> d = {'a':1,'b':2,'c':3}
            >>> print d.exclude_keys('b,c,d')
            >>> {'a':1}
            >>> d = {'a':1,'b':2,'c':3}
            >>> print d.exclude_keys(['b','c','d'])
            >>> {'a':1} """
        if isinstance(key_list,basestring):
            key_list = key_list.split(',')
        return type(self)([ (k,self[k]) for k in self if k not in key_list ])