Access sub bonds in a bond group

[yellowbean]

Deal  {
  bonds ::  Map String Bond
}

Bond = Bond 
     | BondGroup Map String Bond

ie. a bond may have {
   "A" -> BondGroup
                  {"C-1": BondAOne,"C-2": BondATwo}
   ,"B" -> BondB
}

so far, I'm able to refer the Bond Group via "A" as access key.

Quesiton 1: But ,what if I would build a function: => Deal -> String -> Maybe Bond

if input A -> Just BondGroup
if input with "C-1" -> Just BondAOne
if input "B" -> Just BondB
if input "C-2" -> Nothing

Quesiton 2: If possible , I would like to build a lens/optics that would like => Deal -> String -> (Bond -> Bond) -> Deal
which will try it's best to find the bond via the String as key, then update the bond from the function, then return a "updated Deal"

[yellowbean]

resolved by implement function viewDealBondsByNames