context undo

	lex
		ignore /[ ]+/
		literal `;
		token NL /'\n'/
		token id /[a-zA-Z_]+/
	end

	def item 
		[id]

	def start 
		[item* `; NL]
end

Undo: undo = new undo()
parse Input: undo::start( Undo )[ stdin ]
print[ @Input ]
##### IN #####
a b;
##### EXP #####
a b;