code: def create(self, reference, document_data):
          
          write_pbs = _helpers.pbs_for_create(reference._document_path, document_data)
          self._add_write_pbs(write_pbs)
docs: Add a "change" to this batch to create a document.
  
          If the document given by ``reference`` already exists, then this
          batch will fail when :meth:`commit`-ed.
  
          Args:
              reference (~.firestore_v1beta1.document.DocumentReference): A
                  document reference to be created in this batch.
              document_data (dict): Property names and values to use for
                  creating a document.