def echo(value=None):
	print "Execution starts when 'next()' is called for the first time."
	try:
		while True:
			try:
				print "Before yield"
				value = (yield value)
				print "After yield"

			except GeneratorExit:
				print "In GeneratorExit"
				raise StopIteration

			except Exception, e:
				print "In Exception"
				value = e
			
			
	finally:
		print "Don't forget to clean up when 'close()' is called."