class_docstr: Client for working with the Cloud TPU API.
  
  This client is intended to be used for resolving tpu name to ip addresses.
  
  It's recommended to use this library as a contextlib to utilize all
  functionality.
code: def __init__(
      self,
      tpu=None,
      zone=None,
      project=None,
      credentials="default",
      service=None,
      discovery_url=None,
  ):
      if isinstance(tpu, list):
          if not tpu:
              raise ValueError("At least one TPU must be specified.")
          if len(tpu) != 1:
              raise NotImplementedError(
                  "Using multiple TPUs in a single session is not yet implemented"
              )
          tpu = tpu[0]
  
      tpu = _get_tpu_name(tpu)
  
      if tpu is None:
          tpu_node_config = _get_tpu_node_config()
          if tpu_node_config:
              tpu = tpu_node_config.get("tpu_node_name")
              project = project or tpu_node_config.get("project")
              zone = zone or tpu_node_config.get("zone")
          else:
              raise ValueError(
                  "Please provide a TPU Name to connect to."
              )
  
      self._tpu = _as_text(tpu)
  
      self._use_api = not self._tpu.startswith("grpc://")
      self._service = service
  
      self._credentials = None
      self._project = None
      self._zone = None
      self._discovery_url = None
      if self._use_api:
          if credentials != "default":
              self._credentials = credentials
          # Automatically detect project and zone if unspecified.
          if project:
              self._project = _as_text(project)
          else:
              self._project = _request_compute_metadata(
                  "project/project-id"
              )
          if zone:
              self._zone = _as_text(zone)
          else:
              zone_path = _request_compute_metadata("instance/zone")
              self._zone = zone_path.split("/")[-1]
          self._discovery_url = (
              _environment_discovery_url() or discovery_url
          )
  
imports: from concurrent import futures
  import datetime
  import json
  import logging
  import os
  import time
  import urllib
  from absl import flags
label_desc: Use image node_id 1 to create a new Client object  with example: obj = Client(tpu, zone, project, credentials, service, discovery_url)