code: function writePage(resourceId, resourceObj, pathPrefix) {
    const outputPath = resourcePath(resourceId, pathPrefix);
    resourceObj.outputPath = outputPath;
    return write(outputPath, resourceObj.contents);
  }
docs: Take an object's contents and write them to an HTML file on the filesystem.
  @param {String} resourceId   e.g. pages.follow-me.down `.`-separated ID
  representing the hierarchical position of the
  resource in its object structure. Will be used
  to derive output path.
  @param {Object} resourceObj  The object to output. Must have `contents` prop
  @param {String} pathPrefix   The output path prefix (as defined in
  options.dest—@see defaults).
  @return {Promise}