TypeError: unsupported operand type(s) for +: 'NoneType' and 'Fn'

[fabianbauermarquart]

When executing the following adapted example code given in querying/README.md

import torch

import dl2lib as dl2
import dl2lib.query as q
from configargparse import ArgumentParser

from querying.models.mnist.main import Net1

my_pytorch_model = Net1()
my_pytorch_model.load_state_dict(torch.load('models/mnist/mnist_1.pt'))


def high_level_query():
    qtext = """FIND i[10]
    S.T. i[0] + i[3] < NN(i[4])"""  # actualy query
    context = dict()  # a python dict that defines models and named constants
    context['NN'] = my_pytorch_model
    parser = ArgumentParser(description='DL2 Querying')
    parser = dl2.add_default_parser_args(parser, query=True)
    args = parser.parse_args()  # additionaly arguments such as timeout etc.
    success, result, time = q.Query(qtext, context=context, args=args).run()

if __name__ == '__main__':
    high_level_query()

the following error occurs:

Traceback (most recent call last):
  File "~/dl2-master/querying/example_query.py", line 36, in <module>
    variant1()
  File "~/dl2-master/querying/example_query.py", line 21, in variant1
    success, result, time = q.Query(qtext, context=context, args=args).run()
  File "~/dl2-master/dl2lib/query/query.py", line 11, in __init__
    self.constraint, self.return_values = Parser(query, self.context, self.args).parse()
  File "~/dl2-master/dl2lib/query/parser.py", line 42, in parse
    return self.generate_find()
  File "~/dl2-master/dl2lib/query/parser.py", line 50, in generate_find
    constraints = self.traverse_constraints(self.parse_tree.find.constraints.constraints)
  File "~/dl2-master/dl2lib/query/parser.py", line 153, in traverse_constraints
    c1 = self.traverse_constraint(constraint.c1)
  File "~/dl2-master/dl2lib/query/parser.py", line 137, in traverse_constraint
    lhs = self.traverse_expression(constraint.lhs)
  File "~/dl2-master/dl2lib/query/parser.py", line 127, in traverse_expression
    return eval(f"lhs {exp.op} rhs")
  File "<string>", line 1, in <module>
TypeError: unsupported operand type(s) for +: 'NoneType' and 'Fn'

The model mnist_1.pt was trained using the given training procedure train_models.sh from the querying directory.