Fixed new flake8 warnings

astnodes.py

boundaries/createindexlist.py

cpu/cpujit.py

data_types.py

datahandling/datahandling_interface.py

datahandling/serial_datahandling.py

fd/derivation.py

fd/derivative.py

fd/finitedifferences.py

runhelper/db.py

runhelper/parameterstudy.py

simp/assignment_collection.py

sympyextensions.py

transformations.py