for(i=0;True;i++) in python?
<p>Is there a more pythonic way, or at least a shorter and simpler way, to do this:</p>

<pre><code>i = 1
while True:
    res = lookup(i) # returns a value or None
    if res is None:
        break
    else:
        i += 1
        yield res
</code></pre>
