code: def launch_kernel(
      cmd: List[str],
      stdin: Optional[int] = None,
      stdout: Optional[int] = None,
      stderr: Optional[int] = None,
      env: Optional[Dict[str, str]] = None,
      independent: bool = False,
      cwd: Optional[str] = None,
      *,
      _patch_entry_point: bool = True,
      **kw: Any,
  ) -> Popen:
      """Launches a localhost kernel, binding to the specified ports.
  
      Parameters
      ----------
      cmd : Popen list,
          A string of Python code that imports and executes a kernel entry point.
  
      stdin, stdout, stderr : optional (default None)
          Standards streams, as defined in subprocess.Popen.
  
      env: dict, optional
          Environment variables passed to the kernel
  
      independent : bool, optional (default False)
          If set, the kernel process is guaranteed to survive if this process
          dies. If not set, an effort is made to ensure that the kernel is killed
          when this process dies. Note that in this case it is still good practice
          to kill kernels manually before exiting.
  
      cwd : path, optional
          The working dir of the kernel process (default: cwd of this process).
  
      _patch_entry_point: bool, optional
          XXX: by default patches environment to run Python via any python Arcadia binary
          to allow run `sys.executable -m ipykernel.something...` in jupyter_client tests.
  
      **kw: optional
          Additional arguments for Popen
  
      Returns
      -------
  
      Popen instance for the kernel subprocess
      """
  
      # Popen will fail (sometimes with a deadlock) if stdin, stdout, and stderr
      # are invalid. Unfortunately, there is in general no way to detect whether
      # they are valid.  The following two blocks redirect them to (temporary)
      # pipes in certain important cases.
  
      # If this process has been backgrounded, our stdin is invalid. Since there
      # is no compelling reason for the kernel to inherit our stdin anyway, we'll
      # place this one safe and always redirect.
      redirect_in = True
      _stdin = PIPE if stdin is None else stdin
  
      # If this process in running on pythonw, we know that stdin, stdout, and
      # stderr are all invalid.
      redirect_out = sys.executable.endswith("pythonw.exe")
      if redirect_out:
          blackhole = open(os.devnull, "w")  # noqa
          _stdout = blackhole if stdout is None else stdout
          _stderr = blackhole if stderr is None else stderr
      else:
          _stdout, _stderr = stdout, stderr
  
      env = env if (env is not None) else os.environ.copy()
  
      kwargs = kw.copy()
      main_args = {
          "stdin": _stdin,
          "stdout": _stdout,
          "stderr": _stderr,
          "cwd": cwd,
          "env": env,
      }
      kwargs.update(main_args)
  
      # Spawn a kernel.
      if sys.platform == "win32":
          if cwd:
              kwargs["cwd"] = cwd
  
          from .win_interrupt import create_interrupt_event
  
          # Create a Win32 event for interrupting the kernel
          # and store it in an environment variable.
          interrupt_event = create_interrupt_event()
          env["JPY_INTERRUPT_EVENT"] = str(interrupt_event)
          # deprecated old env name:
          env["IPY_INTERRUPT_EVENT"] = env["JPY_INTERRUPT_EVENT"]
  
          try:
              from _winapi import (
                  CREATE_NEW_PROCESS_GROUP,
                  DUPLICATE_SAME_ACCESS,
                  DuplicateHandle,
                  GetCurrentProcess,
              )
          except:  # noqa
              from _subprocess import (
                  CREATE_NEW_PROCESS_GROUP,
                  DUPLICATE_SAME_ACCESS,
                  DuplicateHandle,
                  GetCurrentProcess,
              )
  
          # create a handle on the parent to be inherited
          if independent:
              kwargs["creationflags"] = CREATE_NEW_PROCESS_GROUP
          else:
              pid = GetCurrentProcess()
              handle = DuplicateHandle(
                  pid,
                  pid,
                  pid,
                  0,
                  True,
                  DUPLICATE_SAME_ACCESS,  # Inheritable by new processes.
              )
              env["JPY_PARENT_PID"] = str(int(handle))
  
          # Prevent creating new console window on pythonw
          if redirect_out:
              kwargs["creationflags"] = (
                  kwargs.setdefault("creationflags", 0) | 0x08000000
              )  # CREATE_NO_WINDOW
  
          # Avoid closing the above parent and interrupt handles.
          # close_fds is True by default on Python >=3.7
          # or when no stream is captured on Python <3.7
          # (we always capture stdin, so this is already False by default on <3.7)
          kwargs["close_fds"] = False
      else:
          # Create a new session.
          # This makes it easier to interrupt the kernel,
          # because we want to interrupt the whole process group.
          # We don't use setpgrp, which is known to cause problems for kernels starting
          # certain interactive subprocesses, such as bash -i.
          kwargs["start_new_session"] = True
          if not independent:
              env["JPY_PARENT_PID"] = str(os.getpid())
  
      if _patch_entry_point:
          env["Y_PYTHON_ENTRY_POINT"] = ":main"
  
      try:
          # Allow to use ~/ in the command or its arguments
          cmd = [os.path.expanduser(s) for s in cmd]
          proc = Popen(cmd, **kwargs)  # noqa
      except Exception as ex:
          try:
              msg = "Failed to run command:\n{}\n    PATH={!r}\n    with kwargs:\n{!r}\n"
              # exclude environment variables,
              # which may contain access tokens and the like.
              without_env = {
                  key: value
                  for key, value in kwargs.items()
                  if key != "env"
              }
              msg = msg.format(
                  cmd, env.get("PATH", os.defpath), without_env
              )
              get_logger().error(msg)
          except (
              Exception
          ) as ex2:  # Don't let a formatting/logger issue lead to the wrong exception
              warnings.warn(
                  f"Failed to run command: '{cmd}' due to exception: {ex}",
                  stacklevel=2,
              )
              warnings.warn(
                  f"The following exception occurred handling the previous failure: {ex2}",
                  stacklevel=2,
              )
          raise ex
  
      if sys.platform == "win32":
          # Attach the interrupt event to the Popen object so it can be used later.
          proc.win32_interrupt_event = interrupt_event
  
      # Clean up pipes created to work around Popen bug.
      if redirect_in and stdin is None:
          assert proc.stdin is not None
          proc.stdin.close()
  
      return proc
  
imports: import os
  import sys
  import warnings
  from subprocess import PIPE, Popen
  from typing import Any, Dict, List, Optional
  from traitlets.log import get_logger
label_desc: Use image node_id 1 for calling a global function with example usage: launch_kernel(cmd, stdin, stdout, stderr, env, independent, cwd) and returns: proc