+@name parser.sink
+@return Returns a function that can be used as an ltn12 sink.
+@usage `parser = luci.jsonc.new()
+ltn12.pump.all(ltn12.source.file(io.input()), parser:sink())
+print(parser:get())`
+]]
+
+---[[
+Serialize current parser state as JSON.
+
+@class function
+@sort 5