etnbrd/flx-compiler

digraph G {
  rankdir=LR;
  pad=1;

  graph [ fontname="HelveticaNeue-Thin", fontcolor=black, fontsize=20 ];
  node [ fontname="HelveticaNeue-Thin", fontcolor=black, fontsize=20, penwidth=0.5 shape=circle, fixedsize=true, width=1.2, height=1.2 ];
  edge [ fontname="HelveticaNeue-Thin", fontcolor=black, fontsize=20, penwidth=0.5 splines=line, arrowsize=0.7 ];
  
  subgraph cluster {
    node[shape=plaintext]
    label = "Legend";
    key [fixedsize=false, label=<<table border="0" cellpadding="2" cellspacing="0" cellborder="0">
      <tr><td align="right" port="i1">send message</td></tr>
      </table>>]
    key2 [label=<<table border="0" cellpadding="2" cellspacing="0" cellborder="0">
      <tr><td port="i1">&nbsp;</td></tr>
      </table>>]
    key:i1:e -> key2:i1:w
  }
}