Before revision:  We contribute a formal model that first classifies the type of question based on a taxonomy , and generates an answer based on a set of rules that extract information from representations of an algorithm's internal states, e.g., the pseudocode.
After revision:  We construct XAlgo -- a formal model that first classifies the type of question based on a taxonomy , and generates an answer based on a set of rules that extract information from representations of an algorithm's internal states, e.g., the pseudocode.