docs: def get_initial_beliefs(self):
          """
          Returns the state, action and observation variables as a dictionary
          in the case of table type parameter and a nested structure in case of
          decision diagram parameter
  
          Examples
          --------
          >>> reader = PomdpXReader('Test_PomdpX.xml')
          >>> reader.get_initial_beliefs()
          [{'Var': 'rover_0',
            'Parent': ['null'],
            'Type': 'TBL',
            'Parameter': [{'Instance': ['-'],
            'ProbTable': ['0.0', '1.0', '0.0']}]
           },
           {'Var': '',
            '...': ...,'
            '...': '...',
            }]
          """
          initial_state_belief = []
          for variable in self.network.findall('InitialStateBelief'):
              for var in variable.findall('CondProb'):
                  cond_prob = defaultdict(list)
                  cond_prob['Var'] = var.find('Var').text
                  cond_prob['Parent'] = var.find('Parent').text.split()
                  if not var.find('Parameter').get('type'):
                      cond_prob['Type'] = 'TBL'
                  else:
                      cond_prob['Type'] = var.find('Parameter').get('type')
                  cond_prob['Parameter'] = self.get_parameter(var)
                  initial_state_belief.append(cond_prob)
  
          return initial_state_belief