code: def test_initial_state_belief_dd(self):
      self.model_data = {
          "initial_state_belief": [
              {
                  "Var": "rover_0",
                  "Parent": ["null"],
                  "Type": "DD",
                  "Parameter": {
                      "rover_0": {
                          "s0": "0.0",
                          "s1": {"type": "uniform", "var": "rock_0"},
                          "s2": "0.0",
                      }
                  },
              }
          ]
      }
      self.writer = PomdpXWriter(model_data=self.model_data)
      expected_xml = etree.XML(
          """
  <InitialStateBelief>
    <CondProb>
      <Var>rover_0</Var>
      <Parent>null</Parent>
      <Parameter type="DD">
        <DAG>
          <Node var="rover_0">
            <Edge val="s0">
              <Terminal>0.0</Terminal>
            </Edge>
            <Edge val="s1">
              <SubDAG type="uniform" var="rock_0"/>
            </Edge>
            <Edge val="s2">
              <Terminal>0.0</Terminal>
            </Edge>
          </Node>
        </DAG>
      </Parameter>
    </CondProb>
  </InitialStateBelief>"""
      )
      self.maxDiff = None
      self.assertEqual(
          self.writer.add_initial_belief()
          .decode("utf-8")
          .replace(" ", ""),
          etree.tostring(expected_xml).decode("utf-8").replace(" ", ""),
      )
  
imports: import io
  import sys
  import unittest
  import xml.etree.ElementTree
  from pgmpy.readwrite import PomdpXReader, PomdpXWriter
label_desc: Use image node_id 7 for calling the TestPomdpXWriter obj's underlying member method code with example usage: obj.test_initial_state_belief_dd() without return types