anchor.diff:  
       <%- @graph.right.each do |tokens| -%>
         <%- tokens.select { |t| t.empty_token_sort != 'P' }.each do |token| -%>
  -        <%= node "T#{token.id}", token.form, shape: :none -%>
  +        <%= node "T#{token.id}", token.form, shape: :none, fontcolor: :blue -%>
         <%- end -%>
   
         <%= tokens.select { |t| t.empty_token_sort != 'P' }.map { |token| "T#{token.id}" }.join('->') -%> [style="invis"];
  
positive.code: 
      <%- @graph.left.each do |tokens| -%>
        <%- tokens.select { |t| t.empty_token_sort != 'P' }.each do |token| -%>
          <%= node "T#{token.id}", token.form, shape: :none -%>
        <%- end -%>
  
        <%= tokens.select { |t| t.empty_token_sort != 'P' }.map { |token| "T#{token.id}" }.join('->') -%> [style="invis"];
  
negative.code:   }
  
    <%- @graph.alignments.each do |x, y| -%>
      <%= "T#{x}" -%> -> <%= "T#{y}" -%> [color=blue,dir=none];
    <%- end -%>
  }
  