applyTransforms(baseTemplate, childTemplate, fullRendering) {
        const options = { treeAdapter };
        const rootNodes = fullRendering
            ? parse5.parse(baseTemplate, options)
            : parse5.parseFragment(baseTemplate, options);
        const slotMap =
            childTemplate && typeof childTemplate === 'string'
                ? this._groupSlots(parse5.parseFragment(childTemplate, options))
                : new Map();
        const serializerOptions = {
            treeAdapter,
            slotMap,
            pipeTags: this.pipeTags,
            handleTags: this.handleTags,
            fullRendering
        };
        const serializer = new CustomSerializer(rootNodes, serializerOptions);
        return serializer.serialize();
    }
Parse and serialize the html.

@param {string} baseTemplate - Base template that contains all the necessary tags and fragments for the given page (Used by multiple pages)
@param {string=} childTemplate - The current page template that gets merged in to the base template
@returns {Array} Array consiting of Buffers and Objects