code: def CheckBlobsExist(self, blob_ids, cursor=None):
      
      if not blob_ids:
        return {}
  
      exists = {blob_id: False for blob_id in blob_ids}
      query = ("SELECT blob_id "
               "FROM blobs "
               "FORCE INDEX (PRIMARY) "
               "WHERE blob_id IN {}".format(
                   mysql_utils.Placeholders(len(blob_ids))))
      cursor.execute(query, [blob_id.AsBytes() for blob_id in blob_ids])
      for blob_id, in cursor.fetchall():
        exists[rdf_objects.BlobID.FromBytes(blob_id)] = True
      return exists
docs: Checks if given blobs exist.