GraphSubstitute   157 src/Substitute.cpp     GraphSubstitute(const string &var, const Expr &value) : var(var), value(value) {}
GraphSubstitute   177 src/Substitute.cpp     return GraphSubstitute(name, replacement).mutate(expr);
GraphSubstitute   181 src/Substitute.cpp     return GraphSubstitute(name, replacement).mutate(stmt);