protocols

  scope

classes

  top				something with a line number
    extension			a part of a class definition
    method
      custom method		something written in tom
      builtin method		C operators
    type			something which _is_ a type
      entity			a type with a name
	basic
	meta
	  class
	  instance
      type-tuple
      compound

    expr			some typed thing
      variable			some typed thing with a name
	object variable		an ivar or cvar
      tuple
      invocation


CLASSES

    `Any' is (implicitly or explicitly) the superclass of all other
    classes.  `All' implicitly is the subclass of all other classes.
