STEP contentslist

	command.  Marks the named items for stepping.  Whenever a stepped
	procedure is invoked, each instruction line in the procedure body
	is printed before being executed, and Logo waits for the user to
	type a newline at the terminal.  A message is printed whenever a
	stepped variable name is "shadowed" because a local variable of
	the same name is created either as a procedure input or by the
	LOCAL command.