class_docstr: A variable client for updating variables from a remote source.
docstr: Immediately update and block until we get the result.
code: def update_and_wait(self):
      """Immediately update and block until we get the result."""
      self._copy(self._request())
  
file_path: acme/acme/tf/variable_utils.py
imports: from concurrent import futures
  from typing import Mapping, Optional, Sequence
  from acme import core
  import tensorflow
  import tree
label_desc: Use image node_id 3 for calling the VariableClient obj's underlying member method code with example usage: obj.update_and_wait() without return types