def is_sorted(list_):
    """
    Return True iff list_ is in non-decreasing order.

    @param list list_: list to inspect
    @rtype bool:

    >>> is_sorted([1, 3, 5])
    True
    >>> is_sorted([3, 1, 5])
    False
    """
    for j in range(1, len(list_)):
        if list_[j - 1] > list_[j]:
            return False
    return True