parse(token, context, chain) {
                const state = this;

                return Twig.expression.parseAsync.call(state, token.stack, context)
                    .then(result => {
                        if (chain && Twig.lib.boolval(result)) {
                            chain = false;

                            return state.parseAsync(token.output, context);
                        }

                        return '';
                    })
                    .then(output => {
                        return {
                            chain,
                            output
                        };
                    });
            }
Else if type logic tokens.

 Format: {% elseif expression %}