Any reason this hose is missing?

Hi all, not been on this forum for years but had an unfortunate "incident'' with my golf last year (might go into that some other time) so it's back on my mind. 

Anyway, what does this hose do as it is missing, I just have the top bit coming out and no junction in the other hose. Any reason why it would have been taken out?

Thanks. 

vacuum control valve missing

Sorry, it's not my engine I just got one that shows the hose that's missing as I thought that would make it easier. 
Here's mine
And a close up of someone else's