code: def byte_compare(stream_a, stream_b):
      
      bufsize = 16 * 1024
      equal = True
      ofs = 0
      while True:
          b1 = stream_a.read(bufsize)
          b2 = stream_b.read(bufsize)
          if b1 != b2:
              equal = False
              if b1 and b2:
                  # we have two different buffers: find first mismatch
                  for a, b in zip(b1, b2):
                      if a != b:
                          break
                      ofs += 1
              break
          ofs += len(b1)
          if not b1:  # both buffers empty
              break
      return (equal, ofs)
docs: Byte compare two files (early out on first difference).
  
      Returns:
          (bool, int): offset of first mismatch or 0 if equal