blockdiag {
  node_width = 160;
  node_height = 160;
  span_width = 32;
  span_height = 32;
  default_fontsize = 16;
  default_shape = diamond
  default_node_style = dotted
  default_node_color = red
  default_group_color = blue
  default_linecolor = gray
  default_textcolor = green
  default_label_orientation = vertical

  A -> B;
  group {
    B;
  }
}
