magnify ::
  forall outertag innertag t outer inner m a.
  ( forall x. Coercible (t m x) (m x),
    forall m'.
    (HasReader outertag outer m') =>
    HasReader innertag inner (t m'),
    HasReader outertag outer m
  ) =>
  (forall m'. (HasReader innertag inner m') => m' a) ->
  m a