<?xml version="1.0"?>
<sdf version="1.8">
  <model name="top">
    <model name="mid">
      <link name="link">
        <visual name="visual">
          <geometry>
            <box>
              <size>0.2 0.2 0.2</size>
            </box>
          </geometry>
        </visual>
        <collision name="collision">
          <geometry>
            <box>
              <size>0.2 0.2 0.2</size>
            </box>
          </geometry>
        </collision>
      </link>
    </model>
  </model>
</sdf>
