How to redefine ttAdapter()

test.js

var index = client.initIndex('YourIndexName');
$('input#user_email').typeahead(null, { 
  // source is a function that takes the query and the typeahead.js callback function as parameters
  source: function(query, cb) {
    // perform the search
    index.search(query, function(success, content) { 
      if (success) { 
        // at least one hit ?
        if (content.hits.length > 0) { 
          firstHit = content.hits[0]; 
        }
        // call the regular callback to inform typeahead about the results
        cb(content.hits); 
      } 
    }, { hitsPerPage: 5 }); // force 5 hits only?
  }, 
  name: 'users', 
  displayKey: 'email', 
  templates: { 
    suggestion: function(hit) { 
      return template.render(hit); 
    } 
  }
});