Extract pool attributes from arbitary dict.

def extract_pool_attr(cls, req):
        """ Extract pool attributes from arbitary dict.
        """

        attr = {}
        if 'id' in req:
            attr['id'] = int(req['id'])
        if 'name' in req:
            attr['name'] = req['name']
        if 'description' in req:
            attr['description'] = req['description']
        if 'default_type' in req:
            attr['default_type'] = req['default_type']
        if 'ipv4_default_prefix_length' in req:
            attr['ipv4_default_prefix_length'] = int(req['ipv4_default_prefix_length'])
        if 'ipv6_default_prefix_length' in req:
            attr['ipv6_default_prefix_length'] = int(req['ipv6_default_prefix_length'])

        return attr