Drive.Comments.insert({
  "kind": "drive#comment",
  "author": {
    "kind": "drive#user",
    "displayName": <USER_EMAIL>,  //USER_EMAIL: String
    "isAuthenticatedUser": true,
  },
  "content": <CONTENT>,  //CONTENT: String
  "status": "open",
  "anchor": "{'r':" + <REVISION_ID> + ",'a':[{'txt':{'o':" + <STARTING_OFFSET> + ",'l':" + <OFFSET_LENGTH> + ",'ml':" + <TOTAL_CHARS> + "}}]}",  //REVISION_ID: STRING, STARTING_OFFSET: int, OFFSET_LENGTH: int, TOTAL_CHARS: int
  "fileId": <FILE_ID>  //FILE_ID: String
}, <FILE_ID>);  //FILE_ID: String