code: def migrate(dest_datastore, source_datastore):
          
          for uid in source_datastore.list():
              try:
                  paste = source_datastore._retrieve(uid)
              except Exception as exc:
                  print(
                      "{exc.__class__.__name__} occurred retrieving {uid}: {exc}"
                      .format(exc=exc, uid=uid),
                      file=sys.stderr)
                  continue
              data = paste.pop('data', None)
              try:
                  dest_datastore._store(uid, paste, data)
              except Exception as exc:
                  print(
                      "{exc.__class__.__name__} occurred storing {uid}: {exc}"
                      .format(exc=exc, uid=uid),
                      file=sys.stderr)
                  continue
docs: Copy all records from source_datastore to dest_datastore