Fixing some bugs in Traits we realized that it would be good idea to use CollectionsExtensions package (it has some useful functions), also it would be great to include CollectionsExtensions in Pharo 3.0. 

One "problem" we found is that CollectionsExtensions is depending on a Nile Package (that's not a desired feature). 

In the method Collection>>flatCollect: there is a line refering to a nile function "nsWriteStream".

If i change "nsWriteStream" for "writeStream" the dependency disapears.

I also run all the tests and they are working, so i was wondering if it would be possible to commit the change.

Thanks.