import Charcoal from 'charcoal';

const client = new Charcoal({
  apiKey: process.env['CHARCOAL_API_KEY'], // This is the default and can be omitted
});

const upsertDocumentsResponse = await client.namespaces.documents.upsert('namespace', {
  documents: [{ id: 'id' }],
});

console.log(upsertDocumentsResponse.documents_upserted);

{
  "documents_upserted": 123
}