This iterator generates the names of week day starting from `start` day.

weekday_iterator.py

def weekday_iterator(start=0):
    """ This iterator generates the names 
        of week day starting from `start` day. """
    names = ('mo', 'tu', 'we', 'th', 'fr', 'sa', 'su',)
    maximum = len(names)
    i = 0
    while i < maximum:
        index = (start + i) % maximum
        value = names[index]
        i += 1
        yield (index, value)

Usage:

>>> for i in weekday_iterator(): print i,
... 
mo tu we th fr sa su
>>> for i in weekday_iterator(2): print i,
... 
we th fr sa su mo tu
>>> for i in weekday_iterator(10): print i,
... 
th fr sa su mo tu we
>>>