code: def font_size_to_pixels(size):
      
      if size is None or not isinstance(size, basestring):
          return
      conversions = {'em': 16, 'pt': 16/12.}
      val = re.findall('\d+', size)
      unit = re.findall('[a-z]+', size)
      if (val and not unit) or (val and unit[0] == 'px'):
          return int(val[0])
      elif val and unit[0] in conversions:
          return (int(int(val[0]) * conversions[unit[0]]))
docs: Convert a fontsize to a pixel value