create a monomorphic Iso from pair of functions
view -> from the source of an Iso to the focus of an Iso, review -> from the focus of an Iso to the source of an Iso
lift a polymorphic Iso_ to operate on Bifunctors
monomorphic identity of an Iso
create an Iso from a function that is its own inverse
synonym for apply
lift a polymorphic Iso_ to operate on Functors
if A1 is obtained from A by removing a single value, then Option[A1] is isomorphic to A
A1
A
Option[A1]