def get(self, agentml, user=None, key=None):
user = agentml.get_user(key) if key else user<EOL>if not user:<EOL><INDENT>return<EOL><DEDENT>return user.topic<EOL>
Evaluate and return the current active topic
:param user: The active user object
:type  user: agentml.User or None

:param agentml: The active AgentML instance
:type  agentml: AgentML

:param key: The user id (defaults to the current user if None)
:type  key: str

:return: Active topic of the user
:rtype : str or None