Fix pylint errors (2)
Fix pylint errors (2)

EasonYi/millipede-python,EasonYi/millipede-python,evadot/millipede-python,getmillipede/millipede-python,moul/millipede-python,getmillipede/millipede-python,moul/millipede-python,evadot/millipede-python