@classmethod
def get(cls, type_='bf', **params):
    """Instantiate and return a Session object of the specified type with the specified params."""
    sessions = cls.get_session_types()
    session_module = sessions.get(type_)
    if session_module is None:
        raise ValueError(
            "Invalid session type. Specified type '{}' does not match any registered session type: {}"
            .format(type_, set(sessions.keys())))
    session = session_module(**params)
    return session
