What's the `order` mean in seq.combinations?

Question
1

see: scala seq.combinations returns out of order results - Stack Overflow

It makes me confused in docs of Seq.combinations it says

Iterates over combinations. A combination of length n is a subsequence of the original sequence, with the elements taken in order. Thus, “xy” and “yy” are both length-2 combinations of “xyy”, but “yx” is not. If there is more than one way to generate the same subsequence, only one will be returned.

And it returns

// should here be List("cb", "cc") ?
scala> "cbc".combinations(2).toList
val res23: List[String] = List(cc, cb)

scala> "cba".combinations(2).toList
val res24: List[String] = List(cb, ca, ba)

Does I misunderstanding order here?

2

The behavior when the input includes duplicates is underspecified, it seems to me. You’ll probably need to look at the implementation to figure out what happens in that case. A pull request improving the documentation would be welcome.

3

Thanks your reply, I will try to open a PR later after when I get off work.

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