old_contents: module.exports = (api) => {
    const client = api.client;
    const q = client.queries;
  
    const addInterest = (keyspace, user, type, keyword, next) => {
      const interestValues = [user, type, keyword];
      client.execute(q(keyspace, 'upsertInterest'), interestValues, {}, (err) => {
        if (err) { return next(err); }
        next(null, { user, type, keyword });
      });
    };
  
    const getUsers = (keyspace, type, keyword, next) => {
      api.common.get(keyspace, 'selectUsersByInterest', [type, keyword], 'many', (err, results) => {
        if (err) { return next(err); }
        if (!results) { return next(api.common.error(404, `Unable to find users by interest: ${type}:${keyword}`)); }
        next(null, results);
      });
    };
  
    return {
      addInterest,
      getUsers,
    };
  };
  
new_contents: module.exports = (api) => {
    const client = api.client;
    const q = client.queries;
  
    const addInterest = (keyspace, user, type, keyword, next) => {
      const interestValues = [user, type, keyword];
      client.execute(q(keyspace, 'upsertInterest'), interestValues, {}, (err) => {
        if (err) { return next(err); }
        next(null, { user, type, keyword });
      });
    };
  
    const getUsers = (keyspace, type, keyword, next) => {
      client.execute(q(keyspace, 'selectUsersByInterest'), [type, keyword], {}, (err, results) => {
        if (err) { return next(err); }
        next(null, results);
      });
    };
  
    return {
      addInterest,
      getUsers,
    };
  };
  
subject: use client.execute for getUsers in Interests