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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 _getFontChars(self, font_files):
 """ Returns code points of characters included in given font files. """

        code_points = set()
        for font_file in font_files:
            face = ft.Face(font_file)
            charcode, agindex = face.get_first_char()
            while agindex != 0:
                code_points.add(charcode)
                charcode, agindex = face.get_next_char(charcode, agindex)
        return sorted(code_points)