'Add a callback to be notified when RabbitMQ has sent a
``Connection.Blocked`` frame indicating that RabbitMQ is low on
resources. Publishers can use this to voluntarily suspend publishing,
instead of relying on back pressure throttling. The callback
will be passed the ``Connection.Blocked`` method frame.
See also `ConnectionParameters.blocked_connection_timeout`.
:param method callback_method: Callback to call on `Connection.Blocked`,
having the signature `callback_method(pika.frame.Method)`, where the
method frame\'s `method` member is of type
`pika.spec.Connection.Blocked`'

def add_on_connection_blocked_callback(self, callback_method):

    self.callbacks.add(0, spec.Connection.Blocked, callback_method, False)
