Generators and Iterators in Python

A generator function "yields" its values rather than returning them – and one generator function can yield zero or more results:

def alphabet (): # This is a generator.
   for c in "abcdefghijklmnopqrstuvwxyz":
      yield c

for a in alphabet (): # This is an iterator.
   print a,

# result:
# a b c d e f g h i j k l m n o p q r s t u v w x y z