anchor.diff:  
       open Starling.Core.Model.Pretty
       open Starling.Core.Command.Pretty
  +    open Starling.Core.Symbolic.Pretty
       open Starling.Core.View.Pretty
       open Starling.Core.GuardedView.Pretty
   
  
positive.code: let goalAddAxiom
    (ds : ViewDefiner<_>)
    (fg : FreshGen)
    ((name, axiom) : (string * Axiom<GView<Sym<Var>>, 'cmd>))
    : (string * GoalAxiom<'cmd>) list =
      // Each axiom comes in with a name like method_0,
      // where the 0 is the edge number.
  
negative.code: ///     The new <c>Model</c>, over <c>GoalAxiom</c>s.
  /// </returns>
  let goalAdd
    (mdl : Model<Axiom<IteratedGView<Sym<Var>>, 'cmd>, _>)
    : Model<GoalAxiom<'cmd>, _> =
      // We use a fresh ID generator to ensure every goal variable is unique.
      let fg = freshGen ()
  