mutation {
  CreateDigitalDocument(
title: "A Document"
        contributor: "https://www.cpdl.org"
        creator: "https://www.upf.edu"
        source: "https://www.cpdl.org/A_Document"
        format: "text/html"
        subject: "A document about a topic"
        description: "This is a document"
        language: en
) {
identifier
}
}