Setting nested Options to Some(value)

Hi,

Given a nested chain of Options, is there a way to coerce the most inner one to Some?

The current operator .each allows traversing Options, but acts like map:

import com.softwaremill.quicklens._

case class C(d: Option[Int])
case class B(c: Option[C])
case class A(b: Option[B])

val a = A(b = None)

a.modify(_.b.each.c.each.d.each).setTo(3)  //  res0: A = A(None)

(the result is A(None), but how can we achieve a A(Some(B(Some(C(Some(3))))))?)

It could be useful if there were some operator (say, all) which can act as follows:

a.modify(_.b.all.c.all.d.all).setTo(3) //  res0: A = A(Some(B(Some(C(Some(3))))))

Start by tracing the existing .each operator and how nested Option paths are handled. Evaluate the proposed .all behavior against the examples in this issue, and consider the work complete when setting the nested value produces the requested chain of Some values with appropriate tests.