code: def start(args_string):
      """Launch and display a TensorBoard instance as if at the command line.
  
      Args:
        args_string: Command-line arguments to TensorBoard, to be
          interpreted by `shlex.split`: e.g., "--logdir ./logs --port 0".
          Shell metacharacters are not supported: e.g., "--logdir 2>&1" will
          point the logdir at the literal directory named "2>&1".
      """
      context = _get_context()
      try:
          import IPython
          import IPython.display
      except ImportError:
          IPython = None
  
      if context == _CONTEXT_NONE:
          handle = None
          print("Launching TensorBoard...")
      else:
          handle = IPython.display.display(
              IPython.display.Pretty("Launching TensorBoard..."),
              display_id=True,
          )
  
      def print_or_update(message):
          if handle is None:
              print(message)
          else:
              handle.update(IPython.display.Pretty(message))
  
      parsed_args = shlex.split(args_string, comments=True, posix=True)
      start_result = manager.start(parsed_args)
  
      if isinstance(start_result, manager.StartLaunched):
          _display(
              port=start_result.info.port,
              print_message=False,
              display_handle=handle,
          )
  
      elif isinstance(start_result, manager.StartReused):
          template = (
              "Reusing TensorBoard on port {port} (pid {pid}), started {delta} ago. "
              "(Use '!kill {pid}' to kill it.)"
          )
          message = template.format(
              port=start_result.info.port,
              pid=start_result.info.pid,
              delta=_time_delta_from_info(start_result.info),
          )
          print_or_update(message)
          _display(
              port=start_result.info.port,
              print_message=False,
              display_handle=None,
          )
  
      elif isinstance(start_result, manager.StartFailed):
  
          def format_stream(name, value):
              if value == "":
                  return ""
              elif value is None:
                  return "\n<could not read %s>" % name
              else:
                  return "\nContents of %s:\n%s" % (name, value.strip())
  
          message = (
              "ERROR: Failed to launch TensorBoard (exited with %d).%s%s"
              % (
                  start_result.exit_code,
                  format_stream("stderr", start_result.stderr),
                  format_stream("stdout", start_result.stdout),
              )
          )
          print_or_update(message)
  
      elif isinstance(start_result, manager.StartExecFailed):
          the_tensorboard_binary = (
              "%r (set by the `TENSORBOARD_BINARY` environment variable)"
              % (start_result.explicit_binary,)
              if start_result.explicit_binary is not None
              else "`tensorboard`"
          )
          if start_result.os_error.errno == errno.ENOENT:
              message = (
                  "ERROR: Could not find %s. Please ensure that your PATH contains "
                  "an executable `tensorboard` program, or explicitly specify the path "
                  "to a TensorBoard binary by setting the `TENSORBOARD_BINARY` "
                  "environment variable." % (the_tensorboard_binary,)
              )
          else:
              message = "ERROR: Failed to start %s: %s" % (
                  the_tensorboard_binary,
                  start_result.os_error,
              )
          print_or_update(textwrap.fill(message))
  
      elif isinstance(start_result, manager.StartTimedOut):
          message = (
              "ERROR: Timed out waiting for TensorBoard to start. "
              "It may still be running as pid %d." % start_result.pid
          )
          print_or_update(message)
  
      else:
          raise TypeError(
              "Unexpected result from `manager.start`: %r.\n"
              "This is a TensorBoard bug; please report it."
              % start_result
          )
  
imports: import datetime
  import errno
  import html
  import json
  import os
  import random
  import shlex
  import textwrap
  import time
  from tensorboard import manager
label_desc: Use image node_id 6 for calling a global function with example usage: start(args_string) and returns: str, unknown, unknown