{with {x 3}
      {with {f {fun {y} {+ x y}}}
            {with {x 5}
                  {call f 4}}}}       []

      {with {f {fun {y} {+ x y}}}
            {with {x 5}
                  {call f 4}}}     [(x,3)]

{with {x 5} {call f 4}} [(f,{fun {y} {+ x y}}), (x,3)]

{call f 4}  [(x,5),(f,{fun {y} {+ x y}}),(x,3)]

{+ x y}  [(y,4),(x,5),(f,{fun {y} {+ x y}}),(x,3)]

----------------------------------------------------------------------

{call {with {x 3} {fun {y} {+ x y }}} 4}   []

> {with {x 3} {fun {y} {+ x y}}} []
> {fun {y} {+ x y}} [(x,3)]
=> {fun {y} {+ x y}}
{call {fun {y} {+ x y}} 4}