'Adjusts the value of a given field, specified by \'what\' on a given object id.
Allows modification of certain attributes on newly created or
existing distro object handle.'

def modify_item(self, what, object_id, attribute, arg, token):

    self._log(('modify_item(%s)' % what), object_id=object_id, attribute=attribute, token=token)
    obj = self.__get_object(object_id)
    self.check_access(token, ('modify_%s' % what), obj, attribute)
    method = obj.get_setter_methods().get(attribute, None)
    if (method is None):
        return False
    method(arg)
    return True
