Run from command prompt $> python pipey.py

An example of Pipes and Filters designed to work similarly to the UNIX pipe.
Reads a list of test data (names of Nobel prize winners in physics) and enqueues
them in a pipe. The CapsFilter runs in its own process and continuously reads 
from the Pipe. While this is happening, the WriteFilter opens the sample data 
file and writes each line onto the Pipe. The CapsFilter takes each line off the 
Pipe as it finds them and runs it through its capitalize() method, then prints 
the result to standard out. It keeps trying to read from the Pipe until there is 
no more data on it and it's marked as closed--meaning no more data will be 
arriving. The Pipe uses a multiprocessing.Queue() to pass the data, which is
like a collections.deque that exists in shared memory. This way both filters
can access it despite being in different processes. I also defined a closed
property on Pipe that provides read-only access to the shared memory
multiprocessing.Value().value stored in _closed. To make it possible to see
what's happening in this example, I added a module-level lagify() function that
will randomly delay by 1 second the read or write action to the Pipe. This
makes it easy to see when the WriteFilter finishes writing as theCapsFilter
keeps reading.