             cb         : undefined
         async.parallel([
             (cb) =>
-                query = "UPDATE projects SET hide_from_accounts=hide_from_accounts+{?} WHERE project_id=?"
-                @cql(query, [opts.account_id, opts.project_id], cb)
-            (cb) =>
-                query = "UPDATE accounts SET hidden_projects=hidden_projects+{?} WHERE account_id=?"
-                @cql(query, [opts.project_id, opts.account_id], cb)
+                query = "UPDATE projects SET hide_from_accounts=hide_from_accounts+{#{opts.account_id}} WHERE project_id=?"
+                @cql(query, [opts.project_id], cb)
+            (cb) =>
+                query = "UPDATE accounts SET hidden_projects=hidden_projects+{#{opts.project_id}} WHERE account_id=?"
+                @cql(query, [opts.account_id], cb)
         ], (err) => opts.cb?(err))
 
     unhide_project_from_user: (opts) =>

        async.series([
            # add account_id to the project's set of users (for the given group)
            (cb) =>
                query = "UPDATE projects SET #{opts.group}=#{opts.group}+{?} WHERE project_id=?"
                @cql(query, [opts.account_id, opts.project_id], cb)
            # add project_id to the set of projects (for the given group) for the user's account
            (cb) =>
                query = "UPDATE accounts SET #{opts.group}=#{opts.group}+{?} WHERE account_id=?"
                @cql(query, [opts.project_id, opts.account_id], cb)
        ], opts.cb)

    remove_user_from_project: (opts) =>

        async.series([
            # remove account_id from the project's set of users (for the given group)
            (cb) =>
                query = "UPDATE projects SET #{opts.group}=#{opts.group}-{#{opts.account_id}} WHERE project_id=?"
                @cql(query, [opts.project_id], cb)
            # remove project_id from the set of projects (for the given group) for the user's account
            (cb) =>
                query = "UPDATE accounts SET #{opts.group}=#{opts.group}-{#{opts.project_id}} WHERE account_id=?"
                @cql(query, [opts.account_id], cb)
        ], opts.cb)

    # SINGLE USE ONLY:
