docs: def is_executable_file(path):
      """Checks that path is an executable regular file (or a symlink to a file).
  
      This is roughly ``os.path isfile(path) and os.access(path, os.X_OK)``, but
      on some platforms :func:`os.access` gives us the wrong answer, so this
      checks permission bits directly.
  
      Note
      ----
      This function is taken from the pexpect module, see module doc-string for
      license.
      """
      # follow symlinks,
      fpath = os.path.realpath(path)
  
      # return False for non-files (directories, fifo, etc.)
      if not os.path.isfile(fpath):
          return False
  
      # On Solaris, etc., "If the process has appropriate privileges, an
      # implementation may indicate success for X_OK even if none of the
      # execute file permission bits are set."
      #
      # For this reason, it is necessary to explicitly check st_mode
  
      # get file mode using os.stat, and check if `other',
      # that is anybody, may read and execute.
      mode = os.stat(fpath).st_mode
      if mode & stat.S_IROTH and mode & stat.S_IXOTH:
          return True
  
      # get current user's group ids, and check if `group',
      # when matching ours, may read and execute.
      user_gids = os.getgroups() + [os.getgid()]
      if (os.stat(fpath).st_gid in user_gids and
              mode & stat.S_IRGRP and mode & stat.S_IXGRP):
          return True
  
      # finally, if file owner matches our effective userid,
      # check if `user', may read and execute.
      user_gids = os.getgroups() + [os.getgid()]
      if (os.stat(fpath).st_uid == os.geteuid() and
              mode & stat.S_IRUSR and mode & stat.S_IXUSR):
          return True
  
      return False