MarkovGraphsContainer markov = markovs.get(partition);
assert(markov != null) : "Null MarkovGraphsContainer for partition #" + partition;
graphs_ctr += markov.totalSize();
stringer = (JSONStringer)new JSONStringer().object();
stringer.key(partition.toString()).object();
markov.toJSON(stringer);
stringer.endObject().endObject();
out.write((stringer.toString() + "\n").getBytes());
} // FOR
out.close();