How to add a filter to selection field in odoo
<p>I need to add a filter to a selection field in odoo..</p>

<pre><code>roomuser = fields.Selection([('stpi', 'Belongs to Park'),('Incubation', 'Belongs to Incubation companies'),('both', 'Belongs to Park&amp; Incubation companies')],'Room Assignment',required=True)
roomType = fields.Selection([('meeting','Meeting Room'),('discussion','Discussion Room'),('auditorium','Auditorium'),('board','Board Room')],required=True)
</code></pre>

<p>Here i need to filter the value of roomType based on the value of roomuser. Suppose roomuser value is both only auditorium and board should be visible in roomType</p>