The sample is from our Shoutbox module in Parts.Common.Metadata.Summary-ShoutboxMessage.cshtml.
So what happens here? The WorkContext can contain a "state", i.e. key-value pairs that are only valid for the current request: if a value is set it can be read back later in the same request. We use this to have a value that indicates whether our script was already included or not (think include guards in C, yikes).
Having the same script included in Shoutbox's case would be harmless (it's just a variable declaration) but e.g showing an alert is a use case where you definitely want to prevent the script running more than once!
Happy not flooding the markup with repeated scripts!