code: def setUp(self):
      string = """<pomdpx version="1.0" id="rockSample"
        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
        xsi:noNamespaceSchemaLocation="pomdpx.xsd">
           <Description>RockSample problem for map size 1 x 3.
             Rock is at 0, Rover’s initial position is at 1.
             Exit is at 2.
           </Description>
           <Discount>0.95</Discount>
           <Variable>
                <StateVar vnamePrev="rover_0" vnameCurr="rover_1"
                  fullyObs="true">
                    <NumValues>3</NumValues>
                </StateVar>
                <StateVar vnamePrev="rock_0" vnameCurr="rock_1">
                    <ValueEnum>good bad</ValueEnum>
                </StateVar>
                <ObsVar vname="obs_sensor">
                    <ValueEnum>ogood obad</ValueEnum>
                </ObsVar>
                <ActionVar vname="action_rover">
                    <ValueEnum>amw ame ac as</ValueEnum>
                </ActionVar>
                <RewardVar vname="reward_rover" />
           </Variable>
           <InitialStateBelief>
                <CondProb>
                    <Var>rover_0</Var>
                    <Parent>null</Parent>
                    <Parameter type="TBL">
                          <Entry>
                              <Instance> - </Instance>
                              <ProbTable>0.0 1.0 0.0</ProbTable>
                          </Entry>
                </Parameter>
           </CondProb>
           <CondProb>
                <Var>rock_0</Var>
                <Parent>null</Parent>
                <Parameter type="TBL">
                    <Entry>
                        <Instance>-</Instance>
                        <ProbTable>uniform</ProbTable>
                    </Entry>
                </Parameter>
           </CondProb>
        </InitialStateBelief>
        <StateTransitionFunction>
            <CondProb>
                <Var>rover_1</Var>
                <Parent>action_rover rover_0</Parent>
                <Parameter type="TBL">
                    <Entry>
                        <Instance>amw s0 s2</Instance>
                        <ProbTable>1.0</ProbTable>
                    </Entry>
                    <Entry>
                        <Instance>amw s1 s0</Instance>
                        <ProbTable>1.0</ProbTable>
                    </Entry>
                    <Entry>
                        <Instance>ame s0 s1</Instance>
                        <ProbTable>1.0</ProbTable>
                    </Entry>
                    <Entry>
                        <Instance>ame s1 s2</Instance>
                        <ProbTable>1.0</ProbTable>
                    </Entry>
                    <Entry>
                        <Instance>ac s0 s0</Instance>
                        <ProbTable>1.0</ProbTable>
                    </Entry>
                    <Entry>
                        <Instance>ac s1 s1</Instance>
                        <ProbTable>1.0</ProbTable>
                    </Entry>
                    <Entry>
                        <Instance>as s0 s0</Instance>
                        <ProbTable>1.0</ProbTable>
                    </Entry>
                    <Entry>
                        <Instance>as s1 s2</Instance>
                        <ProbTable>1.0</ProbTable>
                    </Entry>
                    <Entry>
                        <Instance>* s2 s2</Instance>
                        <ProbTable>1.0</ProbTable>
                    </Entry>
             </Parameter>
         </CondProb>
         <CondProb>
             <Var>rock_1</Var>
             <Parent>action_rover rover_0 rock_0</Parent>
             <Parameter>
                 <Entry>
                     <Instance>amw * - - </Instance>
                     <ProbTable>1.0 0.0 0.0 1.0</ProbTable>
                 </Entry>
                 <Entry>
                     <Instance>ame * - - </Instance>
                     <ProbTable>identity</ProbTable>
                 </Entry>
                 <Entry>
                     <Instance>ac * - - </Instance>
                     <ProbTable>identity</ProbTable>
                 </Entry>
                 <Entry>
                     <Instance>as * - - </Instance>
                     <ProbTable>identity</ProbTable>
                 </Entry>
                 <Entry>
                     <Instance>as s0 * - </Instance>
                     <ProbTable>0.0 1.0</ProbTable>
                 </Entry>
             </Parameter>
         </CondProb>
     </StateTransitionFunction>
     <ObsFunction>
         <CondProb>
             <Var>obs_sensor</Var>
             <Parent>action_rover rover_1 rock_1</Parent>
             <Parameter type="TBL">
                 <Entry>
                     <Instance>amw * * - </Instance>
                     <ProbTable>1.0 0.0</ProbTable>
                 </Entry>
                 <Entry>
                     <Instance>ame * * - </Instance>
                     <ProbTable>1.0 0.0</ProbTable>
                 </Entry>
                 <Entry>
                     <Instance>as * * - </Instance>
                     <ProbTable>1.0 0.0</ProbTable>
                 </Entry>
                 <Entry>
                     <Instance>ac s0 - - </Instance>
                     <ProbTable>1.0 0.0 0.0 1.0</ProbTable>
                 </Entry>
                 <Entry>
                     <Instance>ac s1 - - </Instance>
                     <ProbTable>0.8 0.2 0.2 0.8</ProbTable>
                 </Entry>
                  <Entry>
                       <Instance>ac s2 * - </Instance>
                       <ProbTable>1.0 0.0</ProbTable>
                  </Entry>
              </Parameter>
          </CondProb>
      </ObsFunction>
      <RewardFunction>
          <Func>
              <Var>reward_rover</Var>
              <Parent>action_rover rover_0 rock_0</Parent>
              <Parameter type="TBL">
                  <Entry>
                       <Instance>ame s1 *</Instance>
                       <ValueTable>10</ValueTable>
                  </Entry>
                  <Entry>
                       <Instance>amw s0 *</Instance>
                       <ValueTable>-100</ValueTable>
                  </Entry>
                  <Entry>
                       <Instance>as s1 *</Instance>
                       <ValueTable>-100</ValueTable>
                  </Entry>
                  <Entry>
                       <Instance>as s0 good</Instance>
                       <ValueTable>10</ValueTable>
                  </Entry>
                  <Entry>
                       <Instance>as s0 bad</Instance>
                       <ValueTable>-10</ValueTable>
                  </Entry>
              </Parameter>
          </Func>
      </RewardFunction>
   </pomdpx>
   """
      self.reader_string = PomdpXReader(string=string)
      self.reader_file = PomdpXReader(path=io.StringIO(string))
  
imports: import io
  import sys
  import unittest
  import xml.etree.ElementTree
  from pgmpy.readwrite import PomdpXReader, PomdpXWriter
label_desc: Use image node_id 1 for calling the TestPomdpXReaderStringTorch obj's underlying member method code with example usage: obj.setUp() without return types