code: def send_file_to_remote(dev, src_file, dst_filename, filesize, dst_mode='wb'):
      
      bytes_remaining = filesize
      save_timeout = dev.timeout
      dev.timeout = 1
      while bytes_remaining > 0:
          # Wait for ack so we don't get too far ahead of the remote
          ack = dev.read(1)
          if ack is None or ack != b'\x06':
              sys.stderr.write("timed out or error in transfer to remote\n")
              sys.exit(2)
  
          if HAS_BUFFER:
              buf_size = BUFFER_SIZE
          else:
              buf_size = BUFFER_SIZE // 2
          read_size = min(bytes_remaining, buf_size)
          buf = src_file.read(read_size)
          #sys.stdout.write('\r%d/%d' % (filesize - bytes_remaining, filesize))
          #sys.stdout.flush()
          if HAS_BUFFER:
              dev.write(buf)
          else:
              dev.write(binascii.hexlify(buf))
          bytes_remaining -= read_size
      #sys.stdout.write('\r')
      dev.timeout = save_timeout
docs: Intended to be passed to the `remote` function as the xfer_func argument.
         Matches up with recv_file_from_host.