In this page: [boost.compute valarray](https://www.boost.org/doc/libs/1_73_0/libs/compute/doc/html/boost/compute/valarray.html). One can see that `valarray` doesn't have `begin()` and `end()`. Then how can we copy data into `valarray`?
In this page: boost.compute valarray. One can see that
valarraydoesn't havebegin()andend(). Then how can we copy data intovalarray?