code: public static Query withValue(String field,
                                    BinOp op,
                                    Literal value) {
          Query q = new Query(false);
          q.add("field", field).add("op", op.toString()).add("rvalue", value.toJson());
          return q;
      }
docs: <pre>
  { field: <field>, op: <op>, rvalue: <value> }
  </pre>