blocksize = 8192 #262144 # default 8192
local_tmp_filepath.touch(exist_ok=True)
## backward 1 blocksize to ensure data correctness
request_offset = max(0, local_tmp_filepath.stat().st_size - blocksize)
if request_offset > 0:
	print(f"continue downloading at position {request_offset}.")
with local_tmp_filepath.open('r+b') as f:
	f.seek(request_offset)
	ftp_hook.get_conn().retrbinary(f"RETR {str(remote_filepath)}",
				f.write, rest=request_offset, blocksize=blocksize)