code: function(docId, options, ajaxOptions) {
            ajaxOptions = $.extend(ajaxOptions, {
              complete: function(req) {
                var resp = $.parseJSON(req.responseText);
                if (req.status == 201) {
                  if (options.success) options.success(resp);
                } else if (options.error) {
                  options.error(req.status, resp.error, resp.reason);
                } else {
                  throw "The document could not be copied: " + resp.reason;
                }
              }
            });
            ajax({
                type: "COPY",
                url: this.uri + encodeDocId(docId)
              },
              options,
              "The document could not be copied",
              ajaxOptions
            );
          }
docs: The COPY command (which is non-standard HTTP) copies an existing
  document to a new or existing document.
  @see <a href="http://techzone.couchbase.com/sites/default/files/
  uploads/all/documentation/couchbase-api-dbdoc.html#couchbase-api-
  dbdoc_db-doc_copy">docs for COPY /db/doc</a>
  @param {String[]} docId document id to copy
  @param {ajaxSettings} options <a href="http://api.jquery.com/
  jQuery.ajax/#jQuery-ajax-settings">jQuery ajax settings</a>
  @param {ajaxSettings} options <a href="http://api.jquery.com/
  jQuery.ajax/#jQuery-ajax-settings">jQuery ajax settings</a>