open_session

Open a session on the slot.

If the 'auto reuse' setting is set, then this may be a recycled session with the same flags.

This call may block for an indefinite period.

Parameters:

this	The slot ot open a session on.
options	The SessionOptions to open a session with.
cancellable	An optional cancellation object, or null.

Returns:

a new session or null if an error occurs