For unaligned words, we alter all COPY rules in the extracted n-grams to copy tokens by their aligned counterpart, such as replace "params" with "lst", and delete the n-gram subtree, as it is not likely to be relevant in the predicted tree.
some attempts using neural networks have used sequence-to-sequence models (Ling et al., 2016) or tree-based architectures (Dong and Lapata, 2016;Alvarez-Melis and Jaakkola, 2017).