Writes fonts to pys file

def _fonts2pys(self):
        """Writes fonts to pys file"""

        # Get mapping from fonts to fontfiles

        system_fonts = font_manager.findSystemFonts()

        font_name2font_file = {}
        for sys_font in system_fonts:
            font_name = font_manager.FontProperties(fname=sys_font).get_name()
            if font_name in self.fonts_used:
                font_name2font_file[font_name] = sys_font

        # Only include fonts that have been used in the attributes
        for font_name in font_name2font_file:
            # Serialize font
            with open(font_name2font_file[font_name]) as fontfile:
                font_data = fontfile.read()
                ascii_font_data = base64.b64encode(font_data)

            # Store font in pys file
            font_line_list = [font_name, ascii_font_data]
            self.pys_file.write(u"\t".join(font_line_list) + u"\n")