<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def required(self, method, _dict, require):
 """ Ensure the required items are in the dictionary """

        for key in require:
            if key not in _dict:
                raise LunrError("'%s' is required argument for method '%s'"
                                % (key, method))