code: def add(self, arg1, arg2=None, arg3=None, bucket_type=None):
          
          mr = RiakMapReduce(self.client)
          mr.add(self.bucket.name, self.key, bucket_type=bucket_type)
          return mr.add(arg1, arg2, arg3, bucket_type)
docs: Start assembling a Map/Reduce operation.
          A shortcut for :meth:`~riak.mapreduce.RiakMapReduce.add`.
  
          :param arg1: the object or bucket to add
          :type arg1: RiakObject, string
          :param arg2: a key or list of keys to add (if a bucket is
            given in arg1)
          :type arg2: string, list, None
          :param arg3: key data for this input (must be convertible to JSON)
          :type arg3: string, list, dict, None
          :param bucket_type: Optional name of a bucket type
          :type bucket_type: string, None
          :rtype: :class:`~riak.mapreduce.RiakMapReduce`