PEP8: Fixed more issues in eseries.py
PEP8: Fixed more issues in eseries.py

zasdfgbnm/qutip,anubhavvardhan/qutip,zasdfgbnm/qutip,cgranade/qutip,anubhavvardhan/qutip,qutip/qutip,cgranade/qutip,qutip/qutip