code: def pprintHeader(self, prefix=""):
      
      print prefix,
      description = self.getDescription() + [("end", self.getWidth())]
      for i in xrange(len(description) - 1):
        name = description[i][0]
        width = description[i+1][1] - description[i][1]
        formatStr = "%%-%ds |" % width
        if len(name) > width:
          pname = name[0:width]
        else:
          pname = name
        print formatStr % pname,
      print
      print prefix, "-" * (self.getWidth() + (len(description) - 1)*3 - 1)
docs: Pretty-print a header that labels the sub-fields of the encoded
      output. This can be used in conjuction with :meth:`.pprint`.
  
      :param prefix: printed before the header if specified