Box: Box Operations

      $func Box    e.Exp = s.Box;
      $func Get    s.Box = e.Exp;
      $func Store  s.Box e.Exp = ;

Box creates a new box, puts the expression e.Exp into the box, and returns a reference to the box.

Get returns the contents of the box referred to by s.Box.

Store puts the expression e.Box into the box referred to by s.Box.