The ASPCore2.0 standard does not allow explicit conjunctive queries.
Thus, if the input program includes some rules with the query predicate
in their heads, such rules shall be moved to a different data structure
in order to avoid clutter among rules and queries. To make this
operation more efficient, use a list instead of a vector to store the
input program.
Be careful, if the query predicate appers also elsewhere (either in a
body or in a non-atomic head), the eventual query rules shall be
considered part of the input program.