One of the interesting things about Python for compiler geeks is that itis a partially implicit context language, in that line indentation issignificant. Implicit context languages been out of favour for a verylong time, and most parsing techniques these days are geared towardsstream oriented grammars.

(By 'implicit context languages' I mean ones where state changes likeentering and exiting blocks are implicit in the difference betweenlines, such as different indentation levels. By contrast, streamoriented languages use explicit markers for such state changes, like

Python's urllib module convenientlyhandles a great many bits of fetching URLs for you, including HTTP basicauthentication. Unfortunately it does this by pausing everything to 'askthe user for the required information on the controlling terminal' (tomore or less quote from the documentation). This is generally not themost useful behavior in the world, and can even be rather disconcerting.

(A more sensible default behavior would have been to either raise anexception or return a HTTP 'authentication required' status.)

As a