Playground does not give expected result for expansion test c037

Hi,

from expansion algorithm, I don't understand how nesting is supposed to work, especially when step 14.2.2 specifies to "Recursively repeat steps 13 and 14 using nested value for element", but steps 13 and 14 do not modify the active context, so nested values are expanded using the current active context, not the context associated to the nesting key.

I must precise that I'm implementing in a functional language, and it it not clear to me from the wording of the algorithm if active context is passed by reference along recursive calls. By now I assume that it is not the case but I way be wrong. It may be useful to indicate for each algorithm which arguments are passed by rerefence.

Start with the JSON-LD 1.1 expansion algorithm, especially steps 13, 14, and 14.2.2, and compare them with playground expansion test c037. Determine whether active context is intended to be shared through recursive calls and whether the specification should state argument-passing semantics; done means the nesting behavior and wording are unambiguous.