How to identify the subject of a sentence?

Question

Can Python + NLTK be used to identify the subject of a sentence? From what I have learned till now is that a sentence can be broken into a head and its dependents. For e.g.

Answer 1

You can paper over the issue by doing something like doc = nlp(text.decode('utf8')), but this will likely bring you more bugs in future.

Credits: https://github.com/explosion/spaCy/issues/380