docs: def initialize(self, version, force=False):
          """
          Initialize the manifest document in the given datamodel
  
          :param version: Actual version of the datamodel
          :param force: Replace manifest if it already exists
          """
          _check_version_format(version)
          if not force and self.collection.find_one({'_id': 'manifest'}):
              raise DatamodelManifestError("Datamodel has already a manifest")
          manifest = self.collection.update({'_id': 'manifest'}, {
              '_id': 'manifest', 'version': version, 'history': [
                  {'timestamp': datetime.utcnow(), 'version': version,
                   'reason': 'Initialize version'}
              ]}, upsert=True)
          return manifest