new_contents: #!/usr/bin/python
  
  import fontforge
  import sys
  
  # source file
  f = fontforge.open(sys.argv[1])
  # another file for comparsion
  old = fontforge.open(sys.argv[2])
  
  
  fglyphs = set(map(lambda g: g.unicode, f.glyphs()))
  # glyphs in the old file
  oldglyphs = set(map(lambda g: g.unicode, old.glyphs()))
  # intersection - glyphs available in both fonts
  commonglyphs = fglyphs & oldglyphs
  
  print len(fglyphs)
  print len(oldglyphs)
  print len(commonglyphs)
  
  # for each glyph in the edited file:
  for g in f.glyphs():
    # if not present in the second fontfile:
    if not g.unicode in oldglyphs:
      # remove it
      g.clear()
  
  # save the new font - also removing some metadata to save space
  f.generate(sys.argv[3], flags=('omit-instructions', 'no-hints', 'round', 'short-post'))
  
  
subject: Create font-subset-copy.py