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.

It thus seems feasible that by using a similar model, we can produce text samples that are conditioned upon a set of user-specified keywords. To illustrate by example, say a user desires the generated output to contain the keywords, $\lbrace subway, manhattan
brace $ .
What are the user-defined keywords?