docs: def write_pidfile(rundir, process_type=PROCESS_TYPE,
                    name=None, file=None): #@ReservedAssignment
      """
      Write a pid file in the run directory, using the given process type
      and process name for the filename.
  
      @rtype:   str
      @returns: full path to the pid file that was written
      """
      from feat.common.run import get_pidpath
      # don't shadow builtin file
      pid_file = file
      if pid_file is None:
          _ensure_dir(rundir, "rundir")
          filename = get_pidpath(rundir, process_type, name)
          pid_file = open(filename, 'w')
      else:
          filename = pid_file.name
      pid_file.write("%d\n" % (os.getpid(), ))
      pid_file.close()
      os.chmod(filename, 0644)
      return filename