code: function normalizeLink(base, input) {
    assert(input.rel, 'links must have a rel');
    assert(input.href, 'links must have an href');
  
    var ret = clone(input);
  
    ret.rel = normalizeRel(base, input.rel);
    ret.href = normalizeHref(base, input.href);
  
    var cls = normalizeClass(input.class);
    if (cls) ret.class = cls;
  
    return ret;
  }
docs: Takes the `input` link value and normalizes it into a single object.
  
  @param {String} base   The base URL for this API.
  @param {Object} input  The link value to normalize.
  @return {Object}