code: function DocusignAPIError(message, type, code, subcode, traceID) {
    Error.call(this);
    Error.captureStackTrace(this, arguments.callee);
    this.name = 'DocusignAPIError';
    this.message = message;
    this.type = type;
    this.code = code;
    this.subcode = subcode;
    this.traceID = traceID;
    this.status = 500;
  }
docs: `DocusignAPIError` error.
  
  References:
  - https://www.docusign.com/p/RESTAPIGuide/RESTAPIGuide.htm#OAuth2/OAuth2 Response Codes.htm
  
  @constructor
  @param {string} [message]
  @param {string} [type]
  @param {number} [code]
  @param {number} [subcode]
  @param {string} [traceID]
  @access public