def ordered_uniks(iterable):
    """Unique values of iterable in the order they are encountered in arr
    >>> iterable = [4, 2, 6, 1, 2, 2, 7]
    >>> ordered_uniks(iterable)
    [4, 2, 6, 1, 7]
    """
    found = set()
    # Note: (found.add(x) is None) is a trick so that it the expression is always evaluated.
    return [x for x in iterable if x not in found and found.add(x) is None]