def does_not_decrease(s):
    """
    >>> does_not_decrease('1234')
    True
    >>> does_not_decrease('111123')
    True
    >>> does_not_decrease('135679')
    True
    >>> does_not_decrease('223450')
    False
    >>> does_not_decrease('111111')
    True
    >>> does_not_decrease('123789')
    True
    """
    l = [int(c) for c in s]
    for i in range(len(l)-1):
        if l[i] > l[i+1]:
            return False
    return True