For values in the (extended) ASCII range, regardless of Python version.

def rand_str(min_char=MIN_CHR, max_char=MAX_CHR, min_len=MIN_STRLEN, 
             max_len=MAX_STRLEN, func=chr, **kwargs):
    '''For values in the (extended) ASCII range, regardless of Python version.
    '''
    l = randint(min_len, max_len)

    ret = ''
    for k in xrange(l):
        ret += func(randint(min_char, max_char))
    return ret