A list of '@id'

[cardinal27513]

We use rdflib a while and used to serialize data to rdf/xml. There are multiple toplevel graphs in our data, like it is shown in below. There are two "<rdf:Description rdf:about=…/>" in the data set…

<?xml version="1.0" encoding="UTF-8"?>
<rdf:RDF
   xmlns:ns1="http://example.com/ns#"
   xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
>
  <rdf:Description rdf:about="http://example.com/3">
    <rdf:type rdf:resource="http://example.com/ns#Verb_A"/>
    <ns1:hasChild rdf:resource="http://example.com/4"/>
  </rdf:Description>
  <rdf:Description rdf:about="http://example.com/1">
    <rdf:type rdf:resource="http://example.com/ns#Verb_A"/>
    <ns1:hasChild rdf:resource="http://example.com/2"/>
  </rdf:Description>
</rdf:RDF>

When we try to serialize the same graph to json-ld using rdflib-jsonld serializer, the top-level graphs are serialized as “@id” : [ {…} , {…}]
I try this out from the jsonld playground http://json-ld.org/playground/ and it complains that there is syntax error.
{"name":"jsonld.CompactError","message":"Could not expand input before compaction.","details":{"cause":{"name":"jsonld.SyntaxError","message":"Invalid JSON-LD syntax; "@id" value must a string.","details":{}}}}
So is this the bug in jsonld.js or the rdflib-jsonld ?

{
  "@context": {
    "rdf": "http://www.w3.org/1999/02/22-rdf-syntax-ns#",
    "rdfs": "http://www.w3.org/2000/01/rdf-schema#"
  },
  "@id": [
    {
      "@id": "http://example.com/3",
      "@type": "http://example.com/ns#Verb_A",
      "http://example.com/ns#hasChild": {
        "@id": "http://example.com/4"
      }
    },
    {
      "@id": "http://example.com/1",
      "@type": "http://example.com/ns#Verb_A",
      "http://example.com/ns#hasChild": {
        "@id": "http://example.com/2"
      }
    }
  ]
}

[cardinal27513]

Hi Graham,
Just found out that need to replace "@id" with "@graph" at the top level.. that is the new syntax...

digitalbazaar/jsonld.js#9