Module aquarium.parse.ParseAPI

Document the API for parse modules.

These are modules that contain parsing routines, mostly for HTTP headers. There's no official API to follow, but keep the following in mind:

• Some of this code is shared by Glass.
• You should not need a Context object, nor should you subclass AquariumClass. Take a value and return a value. Most of the time, you probably don't even need a class.
• Be prepared to accept None as a header value. This signifies that the header wasn't present.
• If you can do a little more than just parse the header, such as do something related to the header's meaning, all the better, if it prevents code duplication.