code: def __call__(self, orig, dest):
      if (
          not self._proc or self._proc.poll() is not None  # First run.
      ):  # Inkscape terminated.
          env = os.environ.copy()
          # If one passes e.g. a png file to Inkscape, it will try to
          # query the user for conversion options via a GUI (even with
          # `--without-gui`).  Unsetting `DISPLAY` prevents this (and causes
          # GTK to crash and Inkscape to terminate, but that'll just be
          # reported as a regular exception below).
          env.pop("DISPLAY", None)  # May already be unset.
          # Do not load any user options.
          # `os.environ` needs native strings on Py2+Windows.
          env[str("INKSCAPE_PROFILE_DIR")] = os.devnull
          # Old versions of Inkscape (0.48.3.1, used on Travis as of now)
          # seem to sometimes deadlock when stderr is redirected to a pipe,
          # so we redirect it to a temporary file instead.  This is not
          # necessary anymore as of Inkscape 0.92.1.
          self._stderr = TemporaryFile()
          self._proc = subprocess.Popen(
              [str("inkscape"), "--without-gui", "--shell"],
              stdin=subprocess.PIPE,
              stdout=subprocess.PIPE,
              stderr=self._stderr,
              env=env,
          )
          if not self._read_to_prompt():
              raise OSError("Failed to start Inkscape")
  
      try:
          fsencode = os.fsencode
      except AttributeError:  # Py2.
  
          def fsencode(s):
              return s.encode(sys.getfilesystemencoding())
  
      # Inkscape uses glib's `g_shell_parse_argv`, which has a consistent
      # behavior across platforms, so we can just use `shlex.quote`.
      orig_b, dest_b = map(
          _shlex_quote_bytes, map(fsencode, [orig, dest])
      )
      if b"\n" in orig_b or b"\n" in dest_b:
          # Who knows whether the current folder name has a newline, or if
          # our encoding is even ASCII compatible...  Just fall back on the
          # slow solution (Inkscape uses `fgets` so it will always stop at a
          # newline).
          return make_external_conversion_command(
              lambda old, new: [
                  str("inkscape"),
                  "-z",
                  old,
                  "--export-png",
                  new,
              ]
          )(orig, dest)
      self._proc.stdin.write(
          orig_b + b" --export-png=" + dest_b + b"\n"
      )
      self._proc.stdin.flush()
      if not self._read_to_prompt():
          # Inkscape's output is not localized but gtk's is, so the
          # output stream probably has a mixed encoding.  Using
          # `getfilesystemencoding` should at least get the filenames
          # right...
          self._stderr.seek(0)
          raise ImageComparisonFailure(
              self._stderr.read().decode(
                  sys.getfilesystemencoding(), "replace"
              )
          )
  
imports: from __future__ import absolute_import, division, print_function
  import six
  import atexit
  import functools
  import hashlib
  import itertools
  import os
  import re
  import shutil
  import sys
  from tempfile import TemporaryFile
  import numpy
  import matplotlib
  from matplotlib.compat import subprocess
  from matplotlib.testing.exceptions import ImageComparisonFailure
  from matplotlib import _png
  from matplotlib import _get_cachedir
  from matplotlib import cbook
label_desc: Use image node_id 3 for calling the _SVGConverter obj's underlying member method code with example usage: obj.__call__(orig, dest) and returns: make_external_conversion_command, s