def nexus(args): # pragma: no cover
usage = """
Convert a lexibank dataset to nexus.
lexibank nexus <DATASET> --output=...
"""
get_dataset(args)
parser = argparse.ArgumentParser(prog='nexus', usage=usage)
parser.add_argument('--output', help='Nexus output file', default=None)
xargs = parser.parse_args(args.args[1:])
writer = NexusWriter()
if not xargs.output:
print(writer.write())
else:
writer.write_to_file(filename=xargs.output)
