def  foo_ (x : IO Nat) : IO Nat  := x

 def foo (x : IO Nat) : IO Nat  :=  trace  "foo"  (    foo_  x  ) 
tracing: foo
5
private partial  def  bar_ (x : IO Nat) : IO Nat  := baz (pure 5)

private partial  def bar (x : IO Nat) : IO Nat  :=  trace  "bar"  (    bar_  x  )