nl_tokens: produces one or two changes that succinctly describe the changes to the text
pl_tokens: function diffText ( a , b ) { var changes = [ ] var text = a while ( text !== b ) { var c = partiallyDiffText ( text , b ) if ( c . type === 'add' ) { text = <mask> . substr ( 0 , c . index ) + c . value + text . substr ( c . index ) } else { text = text . substr ( 0 , c . index ) + text . substr ( c . index + c . many ) } changes . push ( c ) } return changes }