Given the task definition and input, reply with output. In this task, you will be presented with a context from an academic paper and you have to write an answerable question based on the context. Your questions can be extractive, abstractive, or yes-no questions.

Our search space consists of two stackable cells, one for the model encoder and one for the decoder Each cell contains NASNet-style blocks, which receive two hidden state inputs and produce new hidden states as outputs Our search space contains five branch-level search fields (input, normalization, layer, output dimension and activation), one block-level search field (combiner function) and one cell-level search field (number of cells).
What is in the model search space?