'Registers the given handler to receive the given events for ``fd``.
The ``fd`` argument may either be an integer file descriptor or
a file-like object with a ``fileno()`` method (and optionally a
``close()`` method, which may be called when the `IOLoop` is shut
down).
The ``events`` argument is a bitwise or of the constants
``IOLoop.READ``, ``IOLoop.WRITE``, and ``IOLoop.ERROR``.
When an event occurs, ``handler(fd, events)`` will be run.
.. versionchanged:: 4.0
Added the ability to pass file-like objects in addition to
raw file descriptors.'

def add_handler(self, fd, handler, events):

    raise NotImplementedError()
