https://issues.dlang.org/show_bug.cgi?id=23362

          Issue ID: 23362
           Summary: Permutations should be a forward range
           Product: D
           Version: D2
          Hardware: x86_64
                OS: Linux
            Status: NEW
          Severity: normal
          Priority: P1
         Component: phobos
          Assignee: nobody@puremagic.com
          Reporter: james.gray@remss.net

According to the documentation permutations is a forward range but save is not
implemented. This doesn't compile
```
import std;
    [1,2,3].permutations.save;
```

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