Fix/1289: values with operator is not properly handled @ decorators

[jackey8616]

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Closing issues

closes #1289

[jackey8616]

@WoH Please review, thanks.

[jackey8616]

Currently I only implement minus(-) and plus(+) operator.
The example case can be find in commit c92ee38.

And the latest force-push is rebased to master.
Since I fixed the test @ #1320 .
Now is able to review.

@WoH thanks.

[WoH]

LGTM, thanks!