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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def com_google_fonts_check_fontforge_stderr(font, fontforge_check_results):
 """FontForge validation outputs error messages?"""

  if "skip" in fontforge_check_results:
    yield SKIP, fontforge_check_results["skip"]
    return

  filtered_err_msgs = ""
  for line in fontforge_check_results["ff_err_messages"].split('\n'):
    if ('The following table(s) in the font'
        ' have been ignored by FontForge') in line:
      continue
    if "Ignoring 'DSIG' digital signature table" in line:
      continue
    filtered_err_msgs += line + '\n'

  if len(filtered_err_msgs.strip()) > 0:
    yield WARN, ("FontForge seems to dislike certain aspects of this font file."
                 " The actual meaning of the log messages below is not always"
                 " clear and may require further investigation.\n\n"
                 "{}").format(filtered_err_msgs)
  else:
    yield PASS, "FontForge validation did not output any error message."