'Checks if the socket is known to be closed. We won\'t be aware if it is
until we either use it or have explicitily shut it down.
In practice a socket derived from a port knows about its disconnection
after a failed :func:`~stem.socket.ControlSocket.recv` call. Socket file
derived connections know after either a
:func:`~stem.socket.ControlSocket.send` or
:func:`~stem.socket.ControlSocket.recv`.
This means that to have reliable detection for when we\'re disconnected
you need to continually pull from the socket (which is part of what the
:class:`~stem.control.BaseController` does).
:returns: **bool** that\'s **True** if our socket is connected and **False** otherwise'

def is_alive(self):

    return self._is_alive
