anchor.diff:                failwithf "unsupported expr: %A" expr
   
       gen.Emit(OpCodes.Ret)
  -    let f : Func<'T> = unbox (m.CreateDelegate(typeof<Func<'T>>))
  -    f.Invoke()+
  +    let x = Activator.CreateInstance(typ.CreateType()) :?> ICompiledType<'T>
  +    x.ExecuteCompiledCode()
positive.code:     | i ->
          gen.Emit(OpCodes.Ldc_I4, i)
  
    let compile (expr: Expr<'T>) : 'T =
      let m = DynamicMethod("compiledMethod", typeof<'T>, [||])
  
      let gen = m.GetILGenerator()
  
  
negative.code: open Microsoft.FSharp.Quotations
  open Microsoft.FSharp.Quotations.Patterns
  open System
  open System.Reflection
  open System.Reflection.Emit
  
  module ExprCompiler =
  