Doesn't work.
#!/usr/bin/env python3.0

import sys
foo = b''

for i in range (0,10):
    foo += bytes(i)

sys.stdout.buffer.write(foo)

produces a binary file of 45 bytes. Here is a hex dump (the '.'
represent unprintable characters):
+000    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00     ................
+016    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00     ................
+032    00 00 00 00 00 00 00 00 00 00 00 00 00              .............

that is 45 bytes of 0.