#!/usr/local/bin/python

# This is a really simple example of a coroutine

def printmatcher(matchtext):
    while True:
        line = (yield)           # Notice the use of (yield) as an expression
        if (matchtext in line):
            print matchtext + ": " + line


matcher = printmatcher("Greg")
matcher.next()                  # Advance to the first yield

matcher.send("Sit, Greg, sit")  # Send the string to the coroutine
matcher.send("Watch Phil run")
matcher.send("Hi there, Greg")