anchor.diff:          Expression.emit (value, args, ?loc=range)
   
       let undefined range: Expression =
  -        Expression.name(identifier = Identifier("None"), ?loc=range)
  +        Expression.none()
   
       let getGenericTypeParams (types: Fable.Type list) =
           let rec getGenParams = function
  
positive.code:                        OptimizeTailCall = fun () -> isTailCallOptimized <- true
                         BoundVars = ctx.BoundVars.EnterScope() }
  
          let body =
              if body.Type = Fable.Unit then
                  transformBlock com ctx (Some ReturnUnit) body
  
negative.code: 
              [ Statement.for'(target = target, iter = iter, body = body) ]
  
      let transformFunction com ctx name (args: Fable.Ident list) (body: Fable.Expr) : Arguments * Statement list =
          let tailcallChance =
              Option.map (fun name ->
                  NamedTailCallOpportunity(com, ctx, name, args) :> ITailCallOpportunity) name
  