code: def inventory(self):
          
          dd = self._vivify()
          for platform in self._config.platforms.instances:
              for group in platform.get('groups', ['ungrouped']):
                  instance_name = platform['name']
                  connection_options = self.connection_options(instance_name)
                  molecule_vars = {
                      'molecule_file':
                      "{{ lookup('env', 'MOLECULE_FILE') }}",
                      'molecule_ephemeral_directory':
                      "{{ lookup('env', 'MOLECULE_EPHEMERAL_DIRECTORY') }}",
                      'molecule_scenario_directory':
                      "{{ lookup('env', 'MOLECULE_SCENARIO_DIRECTORY') }}",
                      'molecule_yml':
                      "{{ lookup('file', molecule_file) | molecule_from_yaml }}",
                      'molecule_instance_config':
                      "{{ lookup('env', 'MOLECULE_INSTANCE_CONFIG') }}",
                      'molecule_no_log':
                      "{{ lookup('env', 'MOLECULE_NO_LOG') or not "
                      "molecule_yml.provisioner.log|default(False) | bool }}"
                  }
  
                  # All group
                  dd['all']['hosts'][instance_name] = connection_options
                  dd['all']['vars'] = molecule_vars
                  # Named group
                  dd[group]['hosts'][instance_name] = connection_options
                  dd[group]['vars'] = molecule_vars
                  # Ungrouped
                  dd['ungrouped']['vars'] = {}
                  # Children
                  for child_group in platform.get('children', []):
                      dd[group]['children'][child_group]['hosts'][
                          instance_name] = connection_options
  
          return self._default_to_regular(dd)
docs: Create an inventory structure and returns a dict.
  
          .. code-block:: yaml
              ungrouped:
                vars:
                  foo: bar
                hosts:
                  instance-1:
                  instance-2:
                children:
                  $child_group_name:
                    hosts:
                      instance-1:
                      instance-2:
              $group_name:
                hosts:
                  instance-1:
                    ansible_connection: docker
                  instance-2:
                    ansible_connection: docker
  
          :return: str