<?xml version="1.0"?><gz:world   xmlns:gz='http://playerstage.sourceforge.net/gazebo/xmlschema/#gz'  xmlns:model='http://playerstage.sourceforge.net/gazebo/xmlschema/#model'  xmlns:window='http://playerstage.sourceforge.net/gazebo/xmlschema/#window'  xmlns:params='http://playerstage.sourceforge.net/gazebo/xmlschema/#params'>  <params:GlobalParams>    <gravity>0.0 0.0 -9.8</gravity>  </params:GlobalParams>  <model:ObserverCam>    <id>userCam0</id>    <xyz>-0.279 -4.715 4.388</xyz>    <rpy>0 28 85</rpy>    <window>      <title>Gazebo1</title>      <size>640 480</size>    </window>  </model:ObserverCam>  <model:LightSource>    <id>light0</id>    <xyz>-10.000 -10.000 10.000</xyz>  </model:LightSource>  <model:GroundPlane>    <id>ground1</id>  </model:GroundPlane>  <model:SimpleSolid>    <xyz>0.000 -0.000 -0.000</xyz>    <shape>box</shape>    <size>0.70 0.70 1.50</size>    <color>1.0 1.0 1.0</color>    <model:TruthWidget>      <id>object1</id>    </model:TruthWidget>  </model:SimpleSolid></gz:world>