let request_literal ?(insert_db:bool = true) (sign: bool) (term: term) : literal =
let new_literal = {
sign = sign;
atom = term;
literal_in_db = insert_db;
}
in
try
LiteralTableBase.find global.literals new_literal
with
| Not_found ->
if insert_db then begin
LiteralTableBase.add global.literals new_literal;
end;
new_literal