Return true if the VM is currently 'co-operative' i.e. is expected to reach a balloon target and actually has done

Return value
	type	description
	bool	true if the VM is currently 'co-operative'; false otherwise
Parameters
name	type	description
session_id	session	valid session reference
self	VM	The VM
Errors
name	arguments	description

• Message has both a synchronous and asynchronous version
• This is a custom message