[web2py] Noob Question. How do I make an external link?

[zounds]

I have this in my db.py:

db.define_table('carrier',
    Field('name',),
    Field('url',),
    format='%(name)s')
    
db.define_table('shipment',
    Field('shipment_id', represent=lambda value,row: \
        A(value, _href=(row.carrier.url + value, ))),
    Field('carrier', db.carrier))

The shipment_id link is pointing to 
'http://127.0.0.1:8000/tracker/default/www.bing.com/search?q=trumpet'.  How 
can I make it just 'www.bing.com/search?q=trumpet'.