def print_chain_summary(self, stream=sys.stdout, indent=""):
        """Print a summary of the files in this file dict.

        This version uses chain_input_files and chain_output_files to
        count the input and output files.
        """
        stream.write("%sTotal files      : %i\n" %
                     (indent, len(self.file_dict)))
        stream.write("%s  Input files    : %i\n" %
                     (indent, len(self.chain_input_files)))
        stream.write("%s  Output files   : %i\n" %
                     (indent, len(self.chain_output_files)))
        stream.write("%s  Internal files : %i\n" %
                     (indent, len(self.internal_files)))
        stream.write("%s  Temp files     : %i\n" %
                     (indent, len(self.temp_files)))