Write a recursive ML function that uses pattern matching with name/type
optconcat : char option list -> string
that inputs a list of char options, and returns a single string consisting of all characters on the list concatenated together while ignoring any instances of NONE. For example,
- optconcat([SOME #"b",NONE,SOME #"o",SOME #"o",NONE]);
val it = "boo" : string
- optconcat([NONE,NONE]);
val it = "" : string