from rdflib import Graph
import sys
g = Graph()
filename, ending = sys.argv[1].split('.')
if ending == 'ttl':
g.parse(sys.argv[1], format='ttl')
elif ending == 'rdf':
g.parse(sys.argv[1], format='xml')
with open(f"{filename}.n3", "wb") as f:
f.write(g.serialize(format='ntriples'))