UnboundLocalError: local variable 'zipped_f' referenced before assignment

[cmungall]

the variable zipped_f is only set if -a is passed AND the file does not end with .zip

    if archive and not archive.endswith(".zip"):
        archive += ".zip"
        zipped_f = zipfile.ZipFile(archive, 'w')

so if I say python3 ttl2sif.py -i examples -a gocam-sif.zip -g

it will get to this section

            if archive:
                zpf = zipped_f.open("gocam-sif/" + ttl_file[0:ttl_file.rfind(".")] + ".sif", "w")
                zpf.write(str.encode(sif_content))
                zpf.close()

and zipped_f will be unassigned, leading to the error