How to use the gatsby.Link function in gatsby

var Branding = function Branding(props) {
  var title = props.title,
      subTitle = props.subTitle,
      _props$themeStyle = props.themeStyle,
      themeStyle = _props$themeStyle === undefined ? _branding2.default : _props$themeStyle;


  return _react2.default.createElement(
    _gatsby.Link,
    { className: '' + themeStyle, to: '/' },
    _react2.default.createElement(
      'h1',
      null,
      title
    ),
    _react2.default.createElement(
      'p',
      null,
      subTitle
    )
  );
};

_props$prev = props.prev;
  _props$prev = _props$prev === undefined ? {} : _props$prev;
  var _props$prev$fields = _props$prev.fields;
  _props$prev$fields = _props$prev$fields === undefined ? {} : _props$prev$fields;
  var prevPrefix = _props$prev$fields.prefix,
      prevSlug = _props$prev$fields.slug,
      _props$prev$frontmatt = _props$prev.frontmatter;
  _props$prev$frontmatt = _props$prev$frontmatt === undefined ? {} : _props$prev$frontmatt;
  var prevTitle = _props$prev$frontmatt.title;


  return _react2.default.createElement(
    'div',
    { className: '' + themeStyle },
    prevSlug && _react2.default.createElement(
      _gatsby.Link,
      { to: prevSlug, className: 'prev' },
      PrevIcon && _react2.default.createElement(PrevIcon, null),
      _react2.default.createElement(
        'p',
        null,
        prevTitle,
        ' ',
        _react2.default.createElement(
          'time',
          null,
          prevPrefix
        )
      )
    ),
    nextSlug && _react2.default.createElement(
      _gatsby.Link,

items.map(function (item) {
        var title = item.frontmatter.title,
            slug = item.fields.slug;


        return _react2.default.createElement(
          'li',
          { key: slug },
          _react2.default.createElement(
            _gatsby.Link,
            { to: slug, activeClassName: 'active' },
            title
          )
        );
      })
    )

{ to: prevSlug, className: 'prev' },
      PrevIcon && _react2.default.createElement(PrevIcon, null),
      _react2.default.createElement(
        'p',
        null,
        prevTitle,
        ' ',
        _react2.default.createElement(
          'time',
          null,
          prevPrefix
        )
      )
    ),
    nextSlug && _react2.default.createElement(
      _gatsby.Link,
      { to: nextSlug, className: 'next' },
      NextIcon && _react2.default.createElement(NextIcon, null),
      _react2.default.createElement(
        'p',
        null,
        nextTitle,
        ' ',
        _react2.default.createElement(
          'time',
          null,
          nextPrefix,
          ' '
        )
      )
    )
  );

categories.map(function (category) {
        var link = _react2.default.createElement(
          _gatsby.Link,
          { key: category, to: '/categories/' + category },
          category
        );
        var txt = _react2.default.createElement(
          'span',
          { key: category },
          category
        );

        return categoryLink ? link : txt;
      })
    )

function Header(Props) {
  var siteTitle = Props.siteTitle;
  return React.createElement("header", {
              className: header
            }, React.createElement("div", {
                  className: content
                }, React.createElement("h1", {
                      className: h1
                    }, React.createElement(Gatsby.Link, {
                          to: "/",
                          className: link,
                          children: siteTitle
                        })), React.createElement("nav", {
                      className: nav
                    }, React.createElement(Gatsby.Link, {
                          to: "/blog",
                          className: link,
                          children: "Blog"
                        }))));
}

function Post(Props) {
  var post = Props.post;
  return React.createElement("article", {
              className: article
            }, React.createElement(Gatsby.Link, {
                  to: "/blog/" + post.frontmatter.path,
                  className: link,
                  children: React.createElement("h2", {
                        className: h2
                      }, post.frontmatter.title)
                }), React.createElement("p", {
                  className: p
                }, post.excerpt), React.createElement("small", {
                  className: date
                }, Utils$ReactTemplate.formatDate(post.frontmatter.date)));
}

function Header(Props) {
  var siteTitle = Props.siteTitle;
  return React.createElement("header", {
              className: header
            }, React.createElement("div", {
                  className: content
                }, React.createElement("h1", {
                      className: h1
                    }, React.createElement(Gatsby.Link, {
                          to: "/",
                          className: link,
                          children: siteTitle
                        })), React.createElement("nav", {
                      className: nav
                    }, React.createElement(Gatsby.Link, {
                          to: "/blog",
                          className: link,
                          children: "Blog"
                        }))));
}

items.map(function (item) {
        var _item$frontmatter = item.frontmatter,
            title = _item$frontmatter.title,
            categories = _item$frontmatter.categories,
            _item$fields = item.fields,
            slug = _item$fields.slug,
            prefix = _item$fields.prefix,
            excerpt = item.excerpt;


        return _react2.default.createElement(
          'li',
          { key: slug },
          _react2.default.createElement(
            _gatsby.Link,
            { to: slug },
            _react2.default.createElement(
              'h3',
              null,
              title
            ),
            _react2.default.createElement(_Meta2.default, {
              categories: categories,
              prefix: prefix,
              author: author,
              categoryLink: false,
              icons: metaIcons
            }),
            _react2.default.createElement(
              'p',
              null,

items.map(function (item) {
        var label = item.label,
            to = item.to,
            Icon = item.icon,
            linkProps = item.linkProps;


        return _react2.default.createElement(
          'li',
          { key: label },
          _react2.default.createElement(
            _gatsby.Link,
            _extends({ to: to, activeClassName: 'active' }, linkProps),
            Icon && _react2.default.createElement(Icon, null),
            _react2.default.createElement(
              'span',
              null,
              label
            )
          )
        );
      })
    )