docs: def insert_blob(filename, hosts=None, table=None):
      """Upload a file into a blob table """
      conn = connect(hosts)
      container = conn.get_blob_container(table)
      with open(filename, 'rb') as f:
          digest = container.put(f)
      return '{server}/_blobs/{table}/{digest}'.format(
          server=conn.client.active_servers[0],
          table=table,
          digest=digest
      )