def report_unknown(bytes_so_far, total_size, speed, eta):
sys.stdout.write(<EOL>"<STR_LIT>".format(approximate_size(bytes_so_far),<EOL>approximate_size(speed)))<EOL>sys.stdout.write("<STR_LIT:\r>")<EOL>sys.stdout.flush()<EOL>
This callback for the download function is used
when the total size is unknown