buildGroup = function(group, options) {
                    if (!group) {
                        return new mathMLTree.MathNode("mrow");
                    }

                    if (groupTypes[group.type]) {
                        // Call the groupTypes function
                        return groupTypes[group.type](group, options);
                    } else {
                        throw new ParseError(
                            "Got group of unknown type: '" + group.type + "'");
                    }
                }
Create a new options object with "phantom" set to true.